Layout and operation of pixels for image sensors

ABSTRACT

Various embodiments include methods and apparatuses for forming and using pixels for image sensors. In one embodiment, an image sensor having at least two pixel electrodes per color region, and having at least two modes is disclosed. The example image sensor includes a first, unbinned, mode; and a second, binned, mode. In the first, unbinned mode, the at least two pixel electrodes per color region are to be reset to substantially similar levels. In the second, binned mode, a first pixel electrode of the at the least two pixel electrodes is to be reset to a high voltage that results in efficient collection of photocharge, and a second pixel electrode of the at the least two pixel electrodes is to be reset to a low voltage that results in less efficient collection of photocharge. Other methods and apparatuses are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority benefit of U.S. Provisional PatentApplication No. 62/010,260, entitled, “LAYOUT AND OPERATION OF PIXELSFOR IMAGE SENSORS,” filed Jun. 10, 2014, which is hereby incorporated byreference in its entirety. Each patent, patent application, and/orpublication mentioned in this specification is hereby incorporated byreference in its entirety to the same extent as if each individualpatent, patent application, and/or publication was specifically andindividually indicated to be incorporated by reference.

TECHNICAL FIELD

The present invention generally relates to optical and electronicdevices, systems and methods that include optically sensitive material,such as nanocrystals or other optically sensitive material, and methodsof making and using the devices and systems.

BACKGROUND

Image sensors are desired to provide high-resolution, highsignal-to-noise, and accurate color representations of visual scenes.Frequently, image sensors offer color discrimination using a pattern ofcolor filters, such as the often-employed Bayer Pattern (GR/BG), a 2×2array.

As pixel sizes are reduced to accommodate more pixels per integratedcircuit area, thereby increasing resolution while containing cost, itbecomes increasingly challenging to accommodate all electronic devices,such as transistors, that are needed to provide reset, chargeaccumulation and storage, transfer, shuttering, etc., within the pixelarea. Therefore, it is desirable to provide layouts of pixels that canenable additional transistors to be accommodated, or to allow a givennumber of transistors to be accommodated within a reduced area.

Additionally, microlenses are often employed in image sensors, with onegoal being to focus light through the relevant color filter arrayregion, a strategy that reduces color crosstalk associated with opticalcolor filter array (CFA) crosstalk. Fabrication methods of microlensesatop a square-symmetry array often produce regions at the microlenscorners that are not effective in light focusing, contributing to a lossin fill factor (hence sensitivity) and also a loss of colordiscrimination (hence larger matrix elements in the color correctionmatrix, hence lower signal-to-noise ratio (SNR) in the final de-mosaicedcolor image).

One approach to ensure maximally effective microlenses is to provide alayout of pixels that comes closer to providing circular symmetry in thelayout of the pixels. This may be achieved by increasing the number ofnearest-neighbors, such as in a hexagonal array instead of a squarearray.

BRIEF DESCRIPTION OF THE DRAWINGS

The systems and methods described herein may be understood by referenceto the following figures:

FIGS. 1 and 2 show examples of a hexagonal-packing layout;

FIG. 3 shows a cross-section of a superpixel through the electrodes 1 f,1, 1 c, 2 a of, for example, FIG. 1;

FIG. 4 shows pixel electrodes laid out in a pattern exhibiting anunderlying hexagonal symmetry;

FIG. 5 shows pixel electrodes laid out in a pattern exhibitingunderlying square symmetry;

FIGS. 6A and 6B show hexagonal packing used to provide lowernon-light-sensitive areas compared to square packing;

FIG. 7 shows an example embodiment a high density pixel layout withcolor imaging in binning mode;

FIGS. 8A and 8B, top view and side view, respectively, show a hexagonallayout and a square layout.

FIGS. 9 and 10 show superpixels that comprise subpixels of varying areasof square and hexagonal layouts, respectively;

FIG. 11 shows an example embodiment of stacked pixels;

FIGS. 12A and 12B show hexagonal layouts (trichrome) layouts of stackedpixels;

FIGS. 13A and 13B show square grid (tetrachrome) layouts of stackedpixels;

FIG. 14 shows overall structure and areas according to an embodiment;

FIG. 15 shows an example of a quantum dot 1200;

FIG. 16A shows an aspect of a closed simple geometrical arrangement ofpixels;

FIG. 16B shows an aspect of an open simple geometrical arrangement ofpixels;

FIG. 16C shows a two-row by three-column sub-region within a generallylarger array of top-surface electrodes;

FIG. 17A shows a Bayer filter pattern;

FIG. 17B-17F show examples of some alternative pixel layouts;

FIG. 17G-17L show pixels of different sizes, layouts and types used inpixel layouts;

FIG. 17M shows pixel layouts with different shapes, such as hexagons;

FIG. 17N shows pixel layouts with different shapes, such as triangles;

FIG. 17O shows a quantum dot pixel, such as a multi-spectral quantum dotpixel or other pixel, provided in association with an optical element;

FIG. 17P shows an example of a pixel layout;

FIG. 18 is a block diagram of an example system configuration that maybe used in combination with embodiments described herein;

FIGS. 19A, 19B, and 19C present a cross-section of a CMOS image sensorpixel in which an optically sensitive material has been integrated inintimate contact with the silicon diode;

FIGS. 20A and 20B present cross-sections of a CMOS image sensor pixel inwhich an optically sensitive material has been integrated in intimatecontact with the silicon photodiode;

FIG. 21 is a circuit diagram showing a pixel which has been augmentedwith an optically sensitive material;

FIG. 22 is a cross-section depicting a means of reducing opticalcrosstalk among pixels by incorporating light-blocking layers in thecolor filter array or the passivation or the encapsulation orcombinations thereof;

FIG. 23 is a cross-section depicting a means of reducing crosstalk amongpixels by incorporating light-blocking layers in the color filter arrayor the passivation or the encapsulation or combinations thereof and alsointo the optically sensitive material;

FIGS. 24A-24F are cross-sections depicting a means of fabricating anoptical-crosstalk-reducing structure such as that shown in FIG. 22;

FIG. 25 is a flowchart of an operation of the pixel circuitry;

FIG. 26 illustrates a 3T transistor configuration for interfacing withthe quantum dot material;

FIG. 27 shows an embodiment of a single-plane computing device that maybe used in computing, communication, gaming, interfacing, and so on;

FIG. 28 shows an embodiment of a double-plane computing device that maybe used in computing, communication, gaming, interfacing, and so on;

FIG. 29 shows an embodiment of a camera module that may be used with thecomputing devices of FIG. 27 or FIG. 28;

FIG. 30 shows an embodiment of a light sensor that may be used with thecomputing devices of FIG. 27 or FIG. 28;

FIG. 31 and FIG. 32 show embodiments of methods of gesture recognition;

FIG. 33 shows an embodiment of a three-electrode differential-layoutsystem to reduce external interferences with light sensing operations;

FIG. 34 shows an embodiment of a three-electrode twisted-pair layoutsystem to reduce common-mode noise from external interferences in lightsensing operations;

FIG. 35 is an embodiment of time-modulated biasing a signal applied toelectrodes to reduce external noise that is not at the modulationfrequency;

FIG. 36 shows an embodiment of a transmittance spectrum of a filter thatmay be used in various imaging applications;

FIG. 37 shows an example schematic diagram of a circuit that may beemployed within each pixel to reduce noise power; and

FIG. 38 shows an example schematic diagram of a circuit of aphotoGate/pinned-diode storage that may be implemented in silicon.

Embodiments are described, by way of example only, with reference to theaccompanying drawings. The drawings are not necessarily to scale. Forclarity and conciseness, certain features of the embodiment may beexaggerated and shown in schematic form.

DETAILED DESCRIPTION

With reference to FIG. 1, in this embodiment, each of pixel electrodes1, 1 a, 1 b, 1 c, 2, 2 a, 2 b, etc. are laid out in a hexagonal array.In this example, the pixel electrodes 1, 1 a, . . . , if are responsiblefor sensing a certain color, such as for example green. The pixelelectrodes 2, 2 a, . . . , 2 f are responsible for sensing a certaincolor, such as for example red. Pixel electrodes 3, 3 a, . . . , 3 f areresponsible for sensing a certain color, such as for example blue. Pixelelectrodes 4, 4 a, . . . , 4 f are responsible for sensing a certaincolor, such as, for example, green.

Color discrimination in the aforesaid regions may be implemented using,for example, color filters (a color filter array, CFA) overlying theregions.

Color discrimination in the aforesaid regions may be implemented, in analternative embodiment, by an optically sensitive material having aspecific color sensing capability overlying the regions. For example,the optically sensitive material may sense primarily a specificwavelength, such as green, approximately 500 nm to 580 nm wavelength,and may be considerably less sensitive to other colors, such as blue atapproximately 450 nm to 500 nm, and red, at approximately 580 nm to 650nm.

In the embodiment of FIG. 1, the single-color pixel region 1, 1 a, . . ., 1 f may be said to be spatially oversampled, inasmuch as all sevenpixel electrodes making up this region are responsible for sensingsubstantially the same color.

In a first mode, referred to as unbinned, a signal may be collectedindependently from each of the seven electrodes 1, 1 a, . . . , 1 f.These provide information on the spatial distribution of light impingingupon this “super-region” spanned by electrodes 1, 1 a, . . . , 1 f.

In a second mode, referred to as a binned mode, a signal may becollected from the ensemble, or summation of subsets of, or the entireset, of electrodes 1, 1 a, . . . , 1 f. The binned mode may offer thebenefit of, singly or in combination, faster frame rates, and greatersignal-to-noise ratio, as the signal is the sum of all sub-pixels signaland the noise is the constant readout noise. In this mode, less spatialinformation is conveyed, since the spatial oversampling within theregion spanned by 1, 1 a, . . . , 1 f is not provided.

In a mode referred to as unbinned, the reset level of the seven pixelelectrodes in the region corresponding to 1, 1 a, . . . , 1 f may beselected to be a substantially spatially uniform (e.g., same for 1, 1 a,. . . , 1 f) value. In this manner, electrode 1 collects photochargefrom the region of optically sensitive material that lies closest toelectrode 1; analogously, electrode 1 a collects photocharge from theregion of optically sensitive material that lies closest to electrode 1a; and so on.

In a mode referred to as binned, the reset level of the six pixelelectrodes in the region corresponding to 1, 1 a, . . . , 1 f, may beselected to differ for certain subsets of the list of electrodes. In anexample embodiment, a first reset level may be selected for electrode 1;and a second reset level may be selected for electrodes 1, 1 a, . . . ,1 f. The first reset level and the second reset level may be selectedsuch that photocharge from the regions overlying 1, 1 a, . . . , 1 f,are substantially all collected into electrode 1; and electrodes 1 a, .. . , 1 f do not collect appreciable photocharge. In this exampleembodiment, the photocharge is binned into electrode 1; and electrodes 1a, . . . , 1 f are non-collecting and may not be read.

In a mode referred to as unbinned subsampled, the reset level of asubset of the five pixel electrodes in the region corresponding to 1, 1a, . . . , 1 d may be selected to be a substantially spatially uniform(e.g., same for 1 a, . . . , 1 d) value while the remaining electrodes(e.g., 1) may have a different reset level. In this manner, the firstsubset of electrodes collects photocharge from the region of opticallysensitive material that lies closest to the electrodes while the secondsubset of electrodes remains substantially inactive.

Hexagonal Layout, Four Independently Used Pixel Electrodes

Referring now to FIG. 4, in this embodiment, pixel electrodes 1, 1 a, 1b, 1 c, 2, 2 a, 2 b, 2 c, 3, 3 a, 3 b, 3 c, 4, 4 a, 4 b, and 4 c, arelaid out in a pattern exhibiting an underlying hexagonal symmetry.

Pixel electrodes 1, 1 a, . . . , 1 c are responsible for sensing acertain color, such as for example green. Pixel electrodes 2, 2 a, . . ., 2 c are responsible for sensing a certain color, such as for examplered. Pixel electrodes 3, 3 a, . . . , 3 c are responsible for sensing acertain color, such as for example blue. Pixel electrodes 4, 4 a, . . ., 4 c are responsible for sensing a certain color, such as for examplegreen.

Color discrimination in the aforesaid regions may be implemented using,for example, color filters (a color filter array, CFA) overlying theregions.

Color discrimination in the aforesaid regions may be implemented, in analternative embodiment, by an optically sensitive material having aspecific color sensing capability overlying the regions. For example,the optically sensitive material may sense primarily a specificwavelength, such as green, at approximately 500 nm to 580 nm wavelength,and may be considerably less sensitive to other colors, such as blue, atapproximately 450 nm to 500 nm, and red, at approximately 580 nm to 650nm.

In the embodiment of FIG. 4, the single-color pixel region 1, 1 a, . . ., 1 c may be said to be spatially oversampled, inasmuch as all fourpixel electrodes making up this region are responsible for sensingsubstantially the same color.

In a mode referred to as unbinned, a signal may be collectedindependently from each of the four electrodes 1, 1 a, . . . , 1 c.These provide information on the spatial distribution of light impingingupon this “super-region” spanned by electrodes 1, 1 a, . . . , 1 c.

In a second mode referred to as binned, a signal may be collected fromthe ensemble, or summation of subsets of, or the entire set, ofelectrodes 1, 1 a, . . . , 1 c. The binned mode has the benefit that alarger signal is collected, enabling greater signal-to-noise ratio inthe reported signal. In this mode, less spatial information is conveyed,since the spatial oversampling within the region spanned by 1, 1 a, . .. , 1 c is not provided.

In a mode referred to as unbinned, the reset level of the four pixelelectrodes in the region corresponding to 1, 1 a, . . . , 1 c may beselected to be a substantially spatially uniform (same for 1, 1 a, . . ., 1 c) value. In this manner, electrode 1 collects photocharge from theregion of optically sensitive material that lies closest to electrode 1;analogously, electrode 1 a collects photocharge from the region ofoptically sensitive material that lies closest to electrode 1 a; and soon.

In a mode referred to as binned, the reset level of the four pixelelectrodes in the region corresponding to 1, 1 a, . . . , 1 c, may beselected to differ for certain subsets of the list of electrodes. In anexample embodiment, a first reset level may be selected for electrode 1;and a second reset level may be selected for electrodes 1, 1 a, . . . ,1 c. The first and second reset levels may be selected such thatphotocharge from the regions overlying 1, 1 a, . . . , 1 c, aresubstantially all collected into electrode 1; and electrodes 1 a, . . ., 1 c do not collect appreciable photocharge. In this exampleembodiment, the photocharge is binned into electrode 1; and electrodes 1a, . . . , 1 c are non-collecting and may not be read.

In a mode referred to as unbinned subsampled, the reset level of asubset of the five pixel electrodes in the region corresponding to 1, 1a, . . . , 1 d may be selected to be a substantially spatially uniform(e.g., same for 1 a, . . . , 1 d) value while the remaining electrodes(e.g., 1) may have a different reset level. In this manner, the firstsubset of electrodes collects photocharge from the region of opticallysensitive material that lies closest to the electrodes while the secondsubset of electrodes remains inactive.

Square Layout, Five Independently Used Pixel Electrodes

Referring now to FIG. 5, in this embodiment, pixel electrodes 1, 1 a, 1b, 1 c, 1 d, 2, 2 a, 2 b, 2 c, 2 d, 3, 3 a, 3 b, 3 c, 3 d, 4, 4 a, 4 b,4 c, 4 d, are laid out in a pattern exhibiting underlying squaresymmetry.

Pixel electrodes 1, 1 a, . . . , 1 d are responsible for sensing acertain color, such as for example green. Pixel electrodes 2, 2 a, . . ., 2 d are responsible for sensing a certain color, such as for examplered. Pixel electrodes 3, 3 a, . . . , 3 d are responsible for sensing acertain color, such as for example blue. Pixel electrodes 4, 4 a, . . ., 4 d are responsible for sensing a certain color, such as for examplegreen.

Color discrimination in the aforesaid regions may be implemented using,for example, color filters (a color filter array, CFA) overlying theregions.

Color discrimination in the aforesaid regions may be implemented, in analternative embodiment, an optically sensitive material having aspecific color sensing capability overlying the regions. For example,the optically sensitive material may sense primarily a specificwavelength, such as green, at approximately 500 nm to 580 nm wavelength,and may be considerably less sensitive to other colors, such as blue, atapproximately 450 nm to 500 nm, and red, at approximately 580 nm to 650nm.

In the embodiment of FIG. 5, the single-color pixel region 1, 1 a, . . ., 1 d may be said to be spatially oversampled, inasmuch as all fivepixel electrodes making up this region are responsible for sensingsubstantially the same color.

In a mode referred to as unbinned, a signal may be collectedindependently from each of the four electrodes 1, 1 a, . . . , 1 d.These provide information on the spatial distribution of light impingingupon this “super-region” spanned by electrodes 1, 1 a, . . . , 1 d.

In a second mode referred to as binned, a signal may be collected fromthe ensemble, or summation of subsets of, or the entire set, ofelectrodes 1, 1 a, . . . , 1 d. The binned mode has the benefit that alarger signal is collected, enabling greater signal-to-noise ratio inthe reported signal. In this mode, less spatial information is conveyed,since the spatial oversampling within the region spanned by 1, 1 a, . .. , 1 d is not provided.

In a mode referred to as unbinned, the reset level of the five pixelelectrodes in the region corresponding to 1, 1 a, . . . , 1 d may beselected to be a substantially spatially uniform (same for 1, 1 a, . . ., 1 d) value. In this manner, electrode 1 collects photocharge from theregion of optically sensitive material that lies closest to electrode 1;analogously, electrode 1 a collects photocharge from the region ofoptically sensitive material that lies closest to electrode 1 a; and soon.

In a mode referred to as binned, the reset level of the five pixelelectrodes in the region corresponding to 1, 1 a, . . . , 1 d, may beselected to differ for certain subsets of the list of electrodes. In anexample embodiment, a first reset level may be selected for electrode 1;and a second reset level may be selected for electrodes 1, 1 a, . . . ,1 d. The first and second reset levels may be selected such thatphotocharge from the regions overlying 1, 1 a, . . . , 1 d, aresubstantially all collected into electrode 1; and electrodes 1 a, . . ., 1 d do not collect appreciable photocharge. In this exampleembodiment, the photocharge is binned into electrode 1; and electrodes 1a, . . . , 1 d are non-collecting and may not be read.

In a mode referred to as unbinned subsampled, the reset level of asubset of the five pixel electrodes in the region corresponding to 1, 1a, . . . , 1 d may be selected to be a substantially spatially uniform(e.g., same for 1 a, . . . , 1 d) value while the remaining electrodes(e.g., 1) may have a different reset level. In this manner, the firstsubset of electrodes collects photocharge from the region of opticallysensitive material that lies closest to the electrodes while the secondsubset of electrodes remains substantially inactive.

Comparison of Areas, Resolutions: Advantages of Hexagonal Arrangements

The layouts of FIGS. 4 and 5 may be compared for various arealefficiencies.

Areal Efficiencies

In general, as a rule of thumb, the X number of transistors (X may benon-integer in the case of sharing of at least one transistor amongmultiple pixels) to create a pixel may be fit into a 1.1 μm×1.1 μm areausing a 110 nm process. And thus, 4× transistors may be fit into a 2.2μm×2.2 μm area. This rule of thumb may be expressed: 0.83× transistorsper μm².

Considering the example of FIG. 5, since five transistors are requiredin the region spanned by pixel electrodes 1, 1 a, . . . , 1 d, thisregion possesses an area equal to (5× transistors/0.83×transistors/μm²)=6.05 μm². An integrated circuit providing 8 megapixels'worth of superpixels (e.g., 8 megapixels in binned mode) would thereforerequire an array area of 48.4 mm² of silicon array.

Considering the example of FIG. 4, since 4× transistors are in theregion spanned by pixel electrodes 1, 1 a, . . . , 1 c, this regionpossesses an area equal to (4× transistors/0.83× transistors/μm²)=4.84μm². An integrated circuit providing 8 megapixels' worth of superpixels(e.g., 8 megapixels in binned mode) would therefore require an arrayarea of 38.7 mm² of silicon array.

In these example embodiments, the pixel system arrayed based onhexagonal symmetry offers 8 megapixels in binned mode (highsignal-to-noise) utilization an appreciably lower silicon array area,corresponding to a lower production cost.

The hexagonal symmetry system can provide 32 megapixels worth ofinformation in unbinned mode. The square array system can provide 40megapixels worth of information in unbinned mode. Since there arediminishing returns to growing further the extent of oversampling aftersome point, certain applications may elect the hexagonal symmetryapproach for the benefit of excellent SNR, an impressive oversamplingfactor of 4 times in unbinned mode, and the lower array area.

Variants

In embodiments, the optically sensitive layer may provide sensitivity towavelengths other than visible, such as infrared wavelengths and/orultraviolet wavelengths.

In embodiments, the imaging array may include regions in which theoptically sensitive material is obscured from exposure to light. Suchregions may be termed black pixels. Such pixels may be used to providereferences for levels, offsets, and dark current.

In embodiments, the imaging array may include regions in which theoptically sensitive material is insensitive to light. Such regions maybe termed black pixels. Such pixels may be used to provide referencesfor levels, offsets, and dark current.

In embodiments, two or more pixels covered with the same microlens andcolor filter can be used to detect a phase difference in the image toaid autofocus functionality. In embodiments, two pixels are placed nextto one another laterally, and this structure is employed to detectlateral phase differences. In embodiments, two pixels disposedvertically relative to each other are employed to detect vertical phasedifferences. In embodiments, both vertical and lateral phase differencesare detected to provide maximal enablement of autofocus. In an exampleembodiment, corresponding to the unbinned case in which six pixels areindependent read, phase information along at least three axes can bediscerned.

In embodiments, the dimensions of the superpixel region may be selectedto accommodate at least an additional transistor per superpixel region.This additional transistor(s) may be employed in, for example, providingextra functionality associated with pixel electrode 1, 2, 3, 4. Forexample, these center pixels may be global shutter pixels. They may haveadditional elements between the optically sensitive layer and the sensenode that allow implementation of global shutter operations withoutcompromise to frame rate and integration time. In example embodiments, acurrent-switching approach is provided wherein, during the open-shutterperiod, photocurrent it switched into a charge store; and where, duringthe closed-shutter period, photocurrent is switched to a low-impedancenode.

In embodiments, one or more sub-pixels may include a current-switchingapproach in which, during a first integration period, photocurrent itswitched into a first charge storage element, and during a second periodphotocurrent is switched to a second charge storage element. Inembodiments, a high-dynamic-range imaging system can be provided therebyby employing the first and second charge stores having capacitances thatdiffer by at least twofold. In embodiments, time of flight imaging maybe provided, where the temporal relationship between an emitted briefpulse of light and its incidence onto the time-of-flight sensor isdetected determining the time of switching into the first versus thesecond charge store that maximizes the difference between the signals inthe two charge stores.

In embodiments, the center subpixel of each superpixel region may beselected to provide for a different size of charge store, e.g., adifferent effective capacitance. When read in unbinned mode, theperipheral subpixels 1 a, 1 b, 1 c with their smaller capacitances willoffer higher SNR at the expenses of maximum charge storage, while thecentral subpixel 1 with its higher capacitance will offer a largercharge storage at the expense of SNR in the dark. As a consequence,merging information from 1, 1 a, 1 b, 1 c can provide for extendeddynamic range. This extended dynamic range may be provided even within asingle frame, and even employing a single integration time.

In embodiments, the electronic circuitry used to reset, read, collectcharge, transfer charge, etc., is substantially unilluminated, for theoptically sensitive layer as well as light-obscuring materials betweenthe optically sensitive layer and the electronic circuitry obscure thepassage of light.

In embodiments, circuitry may be included that can provide at least twomodes. Referring again to FIG. 4, in the first mode, the chargecollected by pixel electrodes 1, 1 a, . . . , 1 c, may be conveyed tofour independent charge stores corresponding to 1, 1 a, . . . , 1 c. Inthe second mode, the charge collected by pixel electrodes 1, 1 a, . . ., 1 c, may be conveyed to a single charge store, such as for examplethat originally used for the collection of charge only from pixelelectrode 1. An advantage of this embodiment is that the continuedbiasing of 1, 1 a, . . . , 1 c, at similar reset levels, even in binnedmode, may provide for efficient collection of photocharge from theentire region spanned by 1, 1 a, . . . , 1 c. A disadvantage is that theadditional circuitry used in the switching operation may add area to thecircuit, and also may add noise to the reset process.

The means of color sensing described herein can be combined with meansof color discrimination beyond the use of color filters. For example,the regions of optically sensitive layer may be differently employed indifferent regions to provide color discrimination. In an exampleembodiment, the thickness of the optically sensitive layer may differover superpixel region {1, 1 a, 1 b, 1 c} of FIG. 4, compared to oversuperpixel region {2, 2 a, 2 b, 2 c}. For example, if superpixel region{1, 1 a, 1 b, 1 c} is to provide green sensitivity, the opticallysensitive layer may be of a first thickness, such as 500 nm, over thisregion; and if superpixel region {2, 2 a, 2 b, 2 c} is to provide redsensitivity, the optically sensitive layer may be of a first thickness,such as 800 nm, over this region. One means of providing the differentthickness regions is to produce a top surface of the silicon wafer, ontowhich optically sensitive material is to be deposited, having atopography such that the top surface of the 2, 2 a, 2 b, 2 c region isdeeper by approximately 300 nm than the top surface of 1, 1 a, 1 b, 1 c,e.g., the top surface of the 2 region is recessed by 300 nm compared tothe 1 region.

Referring to FIGS. 6A and 6B, the collecting regions may be visualizedas substantially circular. For example, pixel electrode 1 efficientlycollects from a region of optically sensitive material described by thelarger circle that shares its center with the small-circle labelcorresponding to pixel electrode 1.

Nonuniformly Sized, and Numbered, Subpixels

Referring to FIGS. 9 and 10, superpixels that comprise subpixels ofvarying areas of square and hexagonal layouts, respectively, may beemployed. In the example embodiment of FIG. 9, subregions labeled A maybe sensitive primarily to a first color, subregions B to a second color,and C to a third color. Note that, as illustrated in the figure, thenumber of elements A, B, and C may differ from one another; as well, thecollection areas associated with subpixels of A, B, and C may differfrom one another. The multiple subpixels per superpixel of class A mayoperate in unbinned mode, analogous to the unbinned descriptions above;or they may operate in binned mode, analogous to the binned descriptionsabove; and so on for B and C.

With reference again to FIG. 1, in an example of the high resolutionmode, charges are collected individually into separate small pixelregions defined by a hexagonal layout of high-resolution chargecollecting electrodes 1, 1 a, 1 b, 1 c, 1 d, 1 e, 1 f, 2, 2 a, etc; andin the low-resolution mode, different charge-collecting pixel electrodesand a different pixel circuit are used for the collection ofphotocharges. In the low-resolution mode, the distinct high-resolutionpixels such as 1 a, 1 b, 1 c, . . . 2 a, 2 b, etc. are set tonon-collecting: thus, a distinct pixel circuit is employed in thislow-resolution binned mode. The circuit may incorporate a larger (morecharge capacity) sense node/charge store. The circuit may employ greatercircuit complexity, such as additional transistors, such as transistorsincorporated to implement global electronic shutter, high dynamic range,analog-to-digital conversion, linearization, and the like.

FIG. 2 shows an example of a hexagonal-packing layout of peripheralpixel electrodes 1, 1 a, 1 b, etc. that are used in the high-resolutionmode; and also central pixel electrodes such as 1, 2, 3, etc. that areused in low-resolution mode. In FIG. 2, it is apparent that greatercircuit area 101 may be devoted to sensing region connected to electrode1 used either in low-resolution or high resolution modes compared tosmaller sensing regions 102 connected to electrodes 1 a, 1 b, 1 c, etcused in high-resolution mode.

With reference to FIG. 3, a cross-section of a superpixel through theelectrodes 1 f, 1, 1 c, 2 a shows positions of charge collectingelectrodes 103 connected to photosensitive layer 104, location of topopposite charge collecting electrode 105, locations of color definedlayers 106, and a microlens 107. The microlens 107 is shown in thisexample only over green color and defines a superpixel consisting ofelectrodes 1, 1 a, 1 b, 1 c, 1 d, 1 e, 1 f connected to correspondingsilicon circuits below electrodes.

In a low-resolution binning mode, center electrodes 1, 2, 3, etc. arereset to a certain potential, for example to +2.2 V or to anotherpotential within the range +0.5V to +5V; and peripheral electrodes 1 a,1 b, 1 c, . . . 2 a, etc. are floating and not collecting chargesgenerated in the photon absorbing photosensitive layer 104.

In cases, the peripheral electrodes can be reset to a negative potentialwithin a range of, for example, 0 V to 5 V at certain moments and forcertain period of time to enhance charge collection through centerelectrodes 1, 2, 3, etc., reduce dark current, or reset thephotosensitive layer.

In a high-resolution non-binning mode the peripheral electrodes 1 a, 1b, . . . 2 a, etc. are reset to the same potential, for example +2.2 V,but center electrodes 1, 2, etc. are floating and not collecting thecharges. In certain high-resolution non-binning modes, the electrodesare reset to the same or similar potential to improve SNR utilizingsilicon circuits connected to the center electrodes.

FIGS. 6A and 6B illustrate an advantage of embodiments of the invention.Hexagonal packing may be used to provide lower non-light-sensitive areascompared to square packing Labels 109 point to size and location of oneelectrode either in hexagonal-packing pixel layout (FIG. 6A) whilelabels 108 point to size of charge collecting area within photosensitivelayer defined by potential of the electrode. In this case, radii of allcharge collecting areas may be substantially the same. Notably both inhexagonal packing, FIG. 6A, and in square packing, FIG. 6B, there areshaded areas 110 and 111, respectively, where charge collection is notefficient. When square packing is used, the corners of the square are agreater distance from the collecting pixel electrodes than non-cornerregions of the squares. If photocharges are not efficiently collectedfrom the corner regions, this reduces effective fill factor. Hexagonalimplementations such as shown in FIG. 6A come closer to approximatingrepeat units that are circle-like. Their most remote corners of thehexagons are less distant from the collecting pixel electrode,increasing efficiency and fill factor. By simple calculations the shadednon-charge collecting area 110 of FIG. 6A in hexagonal packing mode isonly 10% of a single pixel area, while shaded non-charge collecting area111 of FIG. 6B in square packing is over 20% of a single pixel area.

Another advantage of the disclosed subject matter includes improvedanti-aliasing. In rectangular grids, there occurs spatial sampling ofhorizontal and vertical spatial frequencies that are periodic.

Aliasing may be reduced using a non-square grid in either highresolution or binning nodes (e.g., as shown in FIG. 1). The pixels canbe sampled non-sequentially, selecting rows and columns connected to amultiple pixels within a superpixel of a specific color. In a layout ofFIG. 1, signals are collected using 2× number of columns compared tosquare grid.

In embodiments, when operating in low-resolution mode (e.g., collectingcurrent into 1, 2, 3, etc. of FIG. 1), the biasing of high-resolutionpixels (1 a, 1 b, 1 c, etc. of FIG. 1) may be selected in order to drivecharge towards the intended collecting pixel 1. If pixel electrode 1 isreset to +2.2 V, and if a transparent top contact is biased at −0.5 V,then the high-resolution pixels not collecting charge may be set to anintermediate voltage, such as +1 V. The biasing of the pixels 1 a, 1 b,1 c etc. may be chosen to minimize dark associated with pixels 1 a, 1 b,1 c, etc.

In embodiments, the dark current flowing into 1 may be determined by thepotential to which 1 a, 1 b, etc. are reset. In embodiments, a darkreference is obtained from dark pixels that employ the same biasingconditions as the illuminated inner array pixels. The dark level equalto the amount acquired by said dark pixels is effectively subtractedfrom reported light pixel values.

In embodiments, a stacked pixel, comprising at least one lower layer oflight sensing material, and a distinct upper layer, is formed. Inembodiments, the stacked pixels are deployed over a hexagonal array.

FIG. 7 shows an example embodiment a high density pixel layout withcolor imaging in binning mode. In one mode, peripheral subpixels 1 a, 1b, 1 c, etc. are non-collecting and the center subpixel 1 collects colorinformation and peripheral subpixels collect all photons within 450-650nm range providing high sensitivity and high resolution imaging after ademosaic process.

FIGS. 8A and 8B, top view and side view, respectively, depict ahexagonal layout and a square layout. This configuration offers anadvantage with respect to crosstalk. A contribution to crosstalk isshape mismatch of a spherical microlens and a pixel. Sizes of aspherical or in some cases aspherical microlenses 112 are typicallysubstantially the same both for hexagonal 113 and square 114 pixels. Theminimum thickness of a microlens is defined by microlens radius ofcurvature and a largest distance across the pixel. In a cross-sectionview in FIG. 8B, along lines A-A′ and B-B′, two adjacent microlenses aretruncated forming a vertical plane in between. In the example of thehexagonal layout, the left portion of FIG. 8B, the height of verticalplane between microlenses 112 is lower than in the example of the squarelayout, the right portion of FIG. 8B. As a result, incoming light rays115 will penetrate into an adjacent pixel by a distance X in thehexagonal layout and by a distance Y in the square layout. The largerdistance Y is directly proportional to a larger optical cross-talk ascompared with the distance X in the hexagonal layout.

Referring now to FIG. 11, an example embodiment of stacked pixels isshown. Each photosensitive layer 118 is separated from another one ofthe photosensitive layers with transparent conductive antireflectionlayers 117. The layers are formed continuously across the pixel arrayexcept for small areas occupied by vias connecting each photosensitivelayer to charge collecting electrodes. In this embodiment, thetransparent conductive antireflection layers 117 are connected outsidethe pixel array to a common counter electrode in one embodiment or to aseparate counter electrodes, one per photosensitive layer.

Bottom electrodes are reset to a certain potential within, for example,a +0.5 V to +5 V range to extract photocharges from each layerseparately. Photocharges are collected by the electrodes 119 located onthe same plane above a silicon circuit.

The antireflection layers 117 are designed to provide total reflectionof blue photons from the two lower photo layers. In it, total reflectionof G photons from incoming rays 116 is provided from the lowest photolayer. In such a stacked pixel, minimal signal processing is required toseparate RGB colors (bottom layer 1—R only, layer 2—R+G, layer3—R+G+B)). Continuous photolayers eliminates the need for a demosaicsignal process.

FIGS. 12A and 12B show hexagonal layouts (trichrome) and FIGS. 13A and13B show square grid (tetrachrome) layouts of stacked pixels with totalcolor EQE above 80%. This is an advantage over traditionalcolor-filter-based systems that reject typically approximately ⅔ of theincident white light through lossy color filtering. Three color-specificelectrodes 120 are located within a full color pixel 121. A specificcolor electrode 122 within each of the full color pixels is sufficientlyseparated from each other to provide high-resolution individual colorimaging to be directly reproduced in matching layout color display,either with the hexagonal layout 123 of FIG. 12B or the square layout127 of FIG. 13B.

FIG. 13A shows a square layout with four different color electrodes 124,125 where electrode 125 is connected to a fourth layer within stackedpixel to collect photons outside the visible range, such as IR, UV,X-Ray. All four electrodes are located within one full color pixel 126.

Various embodiments include a combination of hexagonal-packing layoutand microlenses that allow Shallow Trench Isolation (STI) of superpixelsto reduce cross-talk by either dielectric material or metal which canfunction as (a) a waveguide and (b) as a grid electrode. The 10% areabetween the electrodes has very low areal density of incoming photonsand is used for Trench Isolation without any significant loss ofphotoresponse.

Embodiments include an image sensor comprising a semiconductorsubstrate; a plurality of pixel regions, each pixel region comprising anoptically sensitive material over the substrate, the optically sensitivematerial positioned to receive light; a pixel circuit for each pixelregion, each pixel circuit comprising a charge store formed on thesemiconductor substrate and a read out circuit; and a non-metalliccontact region between the charge store and the optically sensitivematerial of the respective pixel region, wherein the charge store is inelectrical communication with the optically sensitive material of therespective pixel region through the non-metallic contact region.

Embodiments include an image sensor wherein the charge store comprises adoped region of the semiconductor substrate.

Embodiments include an image sensor wherein the charge store comprisesan n-type region of the semiconductor substrate.

Embodiments include an image sensor wherein the charge store comprises adiode.

Embodiments include and image sensor wherein the charge store comprisesa n-type silicon diode.

Embodiments include an image sensor wherein the charge store comprises apinned diode.

Embodiments include an image sensor wherein the pinned diode comprises ap-type layer of the optically sensitive material over an n-type regionof the semiconductor substrate.

Embodiments include an image sensor wherein the optically sensitivematerial comprises a p-type semiconductor material.

Embodiments include an image sensor wherein the non-metallic contactregion comprises a pn junction.

Embodiments include an image sensor wherein the non-metallic contactregion comprises a heterojunction.

Embodiments include an image sensor wherein the optically sensitivematerial is in direct electrical communication with the charge store.

Embodiments include an image sensor wherein the optically sensitivematerial is in direct contact with the charge store.

Embodiments include an image sensor wherein the optically sensitivematerial forms a passivation layer over the charge store.

Embodiments include an image sensor wherein the optically sensitivematerial forms a hole accumulation layer over the charge store.

Embodiments include an image sensor wherein the charge store comprises apinned diode, wherein the pinned diode comprises a p-type layer of theoptically sensitive material over an n-type region of the semiconductorsubstrate.

Embodiments include an image sensor wherein the optically sensitivematerial absorbs light at the wavelength being imaged.

Embodiments include an image sensor wherein the optically sensitivematerial substantially shields the charge store from the light incidenton the optically sensitive layer.

Embodiments include an image sensor wherein the non-metallic contactregion comprises at least one layer of material between the opticallysensitive material and the charge store.

Embodiments include an image sensor wherein the layer of materialcomprises a p-type semiconductor material.

Embodiments include an image sensor wherein the layer of materialcomprises a p-type silicon layer.

Embodiments include an image sensor wherein the layer of materialcomprises a material selected from the group consisting of asemiconductor material, a polymer material and an organic material.

Embodiments include an image sensor wherein the layer of materialprovides a non-metallic conductive path for the flow of charge betweenthe optically sensitive material and the charge store.

Embodiments include an image sensor wherein at least one layer ofmaterial above the charge store substantially shields the charge storefrom the light incident on the optically sensitive layer.

Embodiments include an image sensor wherein the pixel circuit comprisesat least one transistor formed on a first side of the semiconductorsubstrate.

Embodiments include an image sensor wherein the semiconductor substratecomprises metal interconnect on a first side of the semiconductorsubstrate.

Embodiments include an image sensor wherein the charge store is formedon the first side of the semiconductor substrate.

Embodiments include an image sensor wherein the optically sensitivematerial is positioned over the first side of the semiconductorsubstrate.

Embodiments include an image sensor wherein an opening is formed inmetal interconnect layers of the semiconductor substrate to expose thecharge store and the optically sensitive material interfaces with thecharge store through the opening.

Embodiments include an image sensor wherein at least a portion of theoptically sensitive material is positioned in the opening.

Embodiments include an image sensor wherein at least one additionallayer of non-metallic material is included in the opening. Embodimentsinclude an image sensor wherein the charge store is formed on a secondside of the semiconductor substrate.

Embodiments include an image sensor wherein the optically sensitivematerial is positioned over the second side of the semiconductorsubstrate.

Embodiments include an image sensor wherein at least one electrode isproximate the optically sensitive material of each pixel region.

Embodiments include an image sensor wherein the electrode comprises atransparent electrode positioned over the optically sensitive materialof the respective pixel region.

Embodiments include an image sensor wherein the electrode is a lateralelectrode proximate the optically sensitive material of the respectivepixel region.

Embodiments include an image sensor wherein the electrode is a gridelectrode around the optically sensitive material of the respectivepixel region.

Embodiments include an image sensor wherein the electrode is inelectrical communication with a metal interconnect layer of thesemiconductor substrate.

Embodiments include an image sensor wherein the electrode is a commonelectrode for the plurality of pixel regions.

Embodiments include an image sensor wherein the electrode is configuredto provide a bias to the optically sensitive material.

Embodiments include an image sensor wherein the electrode is grounded.

Embodiments include an image sensor wherein the electrode is configuredto provide a voltage lower than a depletion voltage of a pinned diodeforming the charge store.

Embodiments include an image sensor wherein the pixel circuit furthercomprises a sense node.

Embodiments include an image sensor wherein the sense node comprises adoped region of the semiconductor substrate.

Embodiments include an image sensor comprising a charge transfertransistor between the sense node that the charge store for selectivelytransferring charge between the sense node and the charge store when atransfer signal is applied to the gate of the charge transfertransistor.

Embodiments include an image sensor wherein the read out circuitcomprises a source follower transistor and a row select transistor forselectively coupling the source follower transistor to a column read outline.

Embodiments include an image sensor wherein the pixel circuit furthercomprises a reset transistor between the sense node and a referencepotential for selectively resetting the voltage of the sense node when areset signal is applied to the gate of the reset transistor.

Embodiments include an image sensor wherein there are four transistorsincluded in the pixel circuit.

Embodiments include an image sensor wherein the pixel circuit isconfigured to integrate charge from the optically sensitive materialinto the charge store during an integration period of time, wherein thecharge is transferred from the optically sensitive material to thecharge store through the non-metallic contact region.

Embodiments include an image sensor wherein the charge transferred tothe charge store is based on intensity of the light absorbed by theoptically sensitive material of the respective pixel region over anintegration period of time.

Embodiments include an image sensor wherein the pixel circuit isconfigured to provide a read out signal using correlated doublesampling.

Embodiments include an image sensor wherein the pixel circuit isconfigured to perform a first reset, wherein the sense node is reset tothe reference potential and the charge store is reset to a depletionvoltage of a pinned diode forming the charge store.

Embodiments include an image sensor reset transistor and the chargetransfer transistor are open during the first reset.

Embodiments include an image sensor wherein the charge transfertransistor is closed during the integration period of time.

Embodiments include an image sensor wherein the electrode applies avoltage difference across the optically sensitive material during theintegration period of time.

Embodiments include an image sensor wherein the pixel circuit isconfigured to perform a second reset of the sense node prior to readout, wherein the charge transfer transistor is closed and the resettransistor is open during the second reset.

Embodiments include an image sensor wherein the pixel circuit isconfigured to transfer charge from the charge store to the sense nodefor read out after the second reset, wherein the charge transfertransistor is open and the reset transistor is closed during thetransfer of charge from the charge store for read out.

Embodiments include an image sensor wherein the optically sensitivematerial comprises monodispersed nanocrystals.

Embodiments include an image sensor wherein the optically sensitivematerial comprises a continuous film of interconnected nanocrystalparticles in contact with the electrode and the charge store for therespective pixel region.

Embodiments include an image sensor wherein the nanocrystal particlescomprise a plurality of nanocrystal cores and a shell over the pluralityof nanocrystal cores.

Embodiments include an image sensor wherein the plurality of nanocrystalcores is fused.

Embodiments include an image sensor wherein the plurality of nanocrystalcores is electrically interconnected with linker molecules.

Embodiments include an image sensor wherein optical isolation amongpixel regions is achieved using a light-blocking layer disposed in thehorizontal plane substantially at the boundary between the pixelregions.

Embodiments include an image sensor wherein the light-blocking layerconsists of a material from the group Al, TiN, Cu, Ni, Mo, TiOxNy, andW.

Embodiments include an image sensor wherein the light-blocking layerconsists of a material whose width is in the range 5 nm-100 nm.

Embodiments include an image sensor wherein the light-blocking layerconsists of a material whose width is in the range 5 nm-100 nm.

Embodiments include an image sensor comprising a semiconductorsubstrate; a plurality of pixel regions, each pixel region comprising anoptically sensitive material over the substrate, the optically sensitivematerial positioned to receive light; and a pinned diode comprising adoped region of the semiconductor substrate and a portion of theoptically sensitive material over the doped region.

Embodiments include an image sensor wherein the interface between theoptically sensitive material and the doped region forms a pn junction.

Embodiments include an image sensor wherein the interface between theoptically sensitive material and the doped region forms aheterojunction.

Embodiments include a semiconductor substrate; a plurality of pixelregions, each pixel region comprising an optically sensitive materialover the substrate, the optically sensitive material positioned toreceive light; and a diode formed on the semiconductor substrate,wherein the optically sensitive material directly contacts the diode toprovide electrical communication between the optically sensitivematerial and the diode.

Embodiments include an image sensor wherein the interface between theoptically sensitive material and the doped region forms a pn junction.

Embodiments include an image sensor wherein the interface between theoptically sensitive material and the doped region forms aheterojunction.

Embodiments include a method for read out of an image sensor comprising:providing an optically sensitive material over a semiconductorsubstrate; exposing the optically sensitive material to light;integrating charge from the optically sensitive material to a chargestore formed on the semiconductor substrate through a non-metalliccontact region between the optically sensitive material and the chargestore.

Embodiments include the method wherein the charge store is a pinneddiode.

Embodiments include the method wherein the pinned diode is substantiallyshielded from light incident on the optically sensitive material.

Embodiments include the method wherein the optically sensitive materialis the primary location for the absorption of light to be imaged.

Embodiments include a method for read out of an image sensor comprising:providing an optically sensitive material over a semiconductorsubstrate; exposing the optically sensitive material to light;performing a first reset to reset a sense node to a reference potentialand a pinned diode to a depletion voltage level; isolating the pinneddiode from the sense node during an integration period of time;integrating charge from the optically sensitive material to the pinneddiode during the integration period of time, wherein the amount ofcharge integrated during the integration period depends on the intensityof light incident on the photosensitive material; performing a secondreset to reset the sense node prior to read out while the sense node isisolated from the pinned diode; transferring charge from the pinneddiode to the sense node after the second reset; and reading out a signalfrom the sense node.

Embodiments include a method wherein the charge is integrated from theoptically sensitive material to the pinned diode through a directinterface in the absence of metal interconnect between the opticallysensitive material and the pinned diode.

Embodiments include a method wherein the optically sensitive materialinterfaces with the diode to form a pn junction and the charge isintegrated from the optically sensitive material to the diode throughthe interface.

Image sensors incorporate arrays of photodetectors. These photodetectorssense light, converting it from an optical to an electronic signal.

In the description that follows, each drawing refers to an image sensor,or portions of an image sensor that, in example embodiments, would haveone or more of the features, such as (1) direct interface/non-metalliccontact region between film and pinned diode, and/or (2) new pixelcircuit, and/or (3) new pixel isolation techniques, and/or (4) newbackside illumination architecture.

FIG. 14 shows structure of and areas relating to quantum dot pixel chipstructures (QDPCs) 100, according to example embodiments. As illustratedin FIG. 14, the QDPC 100 may be adapted as a radiation 1000 receiverwhere quantum dot structures 1100 are presented to receive the radiation1000, such as light. The QDPC 100 includes quantum dot pixels 1800 and achip 2000 where the chip is adapted to process electrical signalsreceived from the quantum dot pixel 1800. The quantum dot pixel 1800includes the quantum dot structures 1100 include several components andsub components such as quantum dots 1200, quantum dot materials 200 andparticular configurations or quantum dot layouts 300 related to the dots1200 and materials 200. The quantum dot structures 1100 may be used tocreate photodetector structures 1400 where the quantum dot structuresare associated with electrical interconnections 1404. The electricalconnections 1404 are provided to receive electric signals from thequantum dot structures and communicate the electric signals on to pixelcircuitry 1700 associated with pixel structures 1500. Just as thequantum dot structures 1100 may be laid out in various patterns, bothplanar and vertical, the photodetector structures 1400 may haveparticular photodetector geometric layouts 1402. The photodetectorstructures 1400 may be associated with pixel structures 1500 where theelectrical interconnections 1404 of the photodetector structures areelectrically associated with pixel circuitry 1700. The pixel structures1500 may also be laid out in pixel layouts 1600 including vertical andplanar layouts on a chip 2000 and the pixel circuitry 1700 may beassociated with other components 1900, including memory for example. Thepixel circuitry 1700 may include passive and active components forprocessing of signals at the pixel 1800 level. The pixel 1800 isassociated both mechanically and electrically with the chip 2000. Froman electrical viewpoint, the pixel circuitry 1700 may be incommunication with other electronics (e.g. chip processor 2008). Theother electronics may be adapted to process digital signals, analogsignals, mixed signals and the like and it may be adapted to process andmanipulate the signals received from the pixel circuitry 1700. In otherembodiments, a chip processor 2008 or other electronics may be includedon the same semiconductor substrate as the QDPCs and may be structuredusing a system-on-chip architecture. The chip 2000 also includesphysical structures 2002 and other functional components 2004, whichwill also be described in more detail below.

The QDPC 100 detects electromagnetic radiation 1000, which inembodiments may be any frequency of radiation from the electromagneticspectrum. Although the electromagnetic spectrum is continuous, it iscommon to refer to ranges of frequencies as bands within the entireelectromagnetic spectrum, such as the radio band, microwave band,infrared band (IR), visible band (VIS), ultraviolet band (UV), X-rays,gamma rays, and the like. The QDPC 100 may be capable of sensing anyfrequency within the entire electromagnetic spectrum; however,embodiments herein may reference certain bands or combinations of bandswithin the electromagnetic spectrum. It should be understood that theuse of these bands in discussion is not meant to limit the range offrequencies that the QDPC 100 may sense, and are only used as examples.Additionally, some bands have common usage sub-bands, such as nearinfrared (NIR) and far infrared (FIR), and the use of the broader bandterm, such as IR, is not meant to limit the QDPCs 100 sensitivity to anyband or sub-band. Additionally, in the following description, terms suchas “electromagnetic radiation,” “radiation,” “electromagnetic spectrum,”“spectrum,” “radiation spectrum,” and the like are used interchangeably,and the term color is used to depict a select band of radiation 1000that could be within any portion of the radiation 1000 spectrum, and isnot meant to be limited to any specific range of radiation 1000 such asin visible ‘color.’

In the example embodiment of FIG. 14, the nanocrystal materials andphotodetector structures described above may be used to provide quantumdot pixels 1800 for a photosensor array, image sensor or otheroptoelectronic device. In example embodiments, the pixels 1800 includequantum dot structures 1100 capable of receiving radiation 1000,photodetectors structures adapted to receive energy from the quantum dotstructures 1100 and pixel structures. The quantum dot pixels describedherein can be used to provide the following in some embodiments: highfill factor, potential to bin, potential to stack, potential to go tosmall pixel sizes, high performance from larger pixel sizes, simplifycolor filter array, elimination of de-mosaicing, self-gainsetting/automatic gain control, high dynamic range, global shuttercapability, auto-exposure, local contrast, speed of readout, low noisereadout at pixel level, ability to use larger process geometries (lowercost), ability to use generic fabrication processes, use digitalfabrication processes to build analog circuits, adding other functionsbelow the pixel such as memory, A to D, true correlated double sampling,binning, etc. Example embodiments may provide some or all of thesefeatures. However, some embodiments may not use these features.

A quantum dot 1200 may be a nanostructure, typically a semiconductornanostructure, that confines a conduction band electrons, valence bandholes, or excitons (bound pairs of conduction band electrons and valenceband holes) in all three spatial directions. A quantum dot exhibits inits absorption spectrum the effects of the discrete quantized energyspectrum of an idealized zero-dimensional system. The wave functionsthat correspond to this discrete energy spectrum are typicallysubstantially spatially localized within the quantum dot, but extendover many periods of the crystal lattice of the material.

FIG. 15 shows an example of a quantum dot 1200. In one exampleembodiment, the QD 1200 has a core 1220 of a semiconductor or compoundsemiconductor material, such as PbS. Ligands 1225 may be attached tosome or all of the outer surface or may be removed in some embodimentsas described further below. In embodiments, the cores 1220 of adjacentQDs may be fused together to form a continuous film of nanocrystalmaterial with nanoscale features. In other embodiments, cores may beconnected to one another by linker molecules.

Some embodiments of the QD optical devices are single image sensor chipsthat have a plurality of pixels, each of which includes a QD layer thatis radiation 1000 sensitive, e.g., optically active, and at least twoelectrodes in electrical communication with the QD layer. The currentand/or voltage between the electrodes is related to the amount ofradiation 1000 received by the QD layer. Specifically, photons absorbedby the QD layer generate electron-hole pairs, such that, if anelectrical bias is applied, a current flows. By determining the currentand/or voltage for each pixel, the image across the chip can bereconstructed. The image sensor chips have a high sensitivity, which canbe beneficial in low-radiation-detecting 1000 applications; a widedynamic range allowing for excellent image detail; and a small pixelsize. The responsivity of the sensor chips to different opticalwavelengths is also tunable by changing the size of the QDs in thedevice, by taking advantage of the quantum size effects in QDs. Thepixels can be made as small as 1 square micron or less, such as 700×700nm, or as large as 30 by 30 microns or more or any range subsumedtherein.

The photodetector structure 1400 is a device configured so that it canbe used to detect radiation 1000 in example embodiments. The detectormay be ‘tuned’ to detect prescribed wavelengths of radiation 1000through the types of quantum dot structures 1100 that are used in thephotodetector structure 1400. The photodetector structure can bedescribed as a quantum dot structure 1100 with an I/O for someinput/output ability imposed to access the quantum dot structures' 1100state. Once the state can be read, the state can be communicated topixel circuitry 1700 through an electrical interconnection 1404, whereinthe pixel circuitry may include electronics (e.g., passive and/oractive) to read the state. In an embodiment, the photodetector structure1400 may be a quantum dot structure 1100 (e.g., film) plus electricalcontact pads so the pads can be associated with electronics to read thestate of the associated quantum dot structure.

In embodiments, processing my include binning of pixels in order toreduce random noise associated with inherent properties of the quantumdot structure 1100 or with readout processes. Binning may involve thecombining of pixels 1800, such as creating 2×2, 3×3, 5×5, or the likesuperpixels. There may be a reduction of noise associated with combiningpixels 1800, or binning, because the random noise increases by thesquare root as area increases linearly, thus decreasing the noise orincreasing the effective sensitivity. With the QDPC's 100 potential forvery small pixels, binning may be utilized without the need to sacrificespatial resolution, that is, the pixels may be so small to begin withthat combining pixels doesn't decrease the required spatial resolutionof the system. Binning may also be effective in increasing the speedwith which the detector can be run, thus improving some feature of thesystem, such as focus or exposure.

In embodiments the chip may have functional components that enablehigh-speed readout capabilities, which may facilitate the readout oflarge arrays, such as 5 Mpixels, 6 Mpixels, 8 Mpixels, 12 Mpixels, 24Mpixels, or the like. Faster readout capabilities may require morecomplex, larger transistor-count circuitry under the pixel 1800 array,increased number of layers, increased number of electricalinterconnects, wider interconnection traces, and the like.

In embodiments, it may be desirable to scale down the image sensor sizein order to lower total chip cost, which may be proportional to chiparea. Embodiments include the use of micro-lenses. Embodiments includeusing smaller process geometries.

In embodiments, pixel size, and thus chip size, may be scaled downwithout decreasing fill factor. In embodiments, larger processgeometries may be used because transistor size, and interconnectline-width, may not obscure pixels since the photodetectors are on thetop surface, residing above the interconnect. In embodiments, geometriessuch as 90 nm, 0.13 μm and 0.18 μm may be employed without obscuringpixels. In embodiments, small geometries such as 90 nm and below mayalso be employed, and these may be standard, rather thanimage-sensor-customized, processes, leading to lower cost. Inembodiments, the use of small geometries may be more compatible withhigh-speed digital signal processing on the same chip. This may lead tofaster, cheaper, and/or higher-quality image sensor processing on chip.In embodiments, the use of more advanced geometries for digital signalprocessing may contribute to lower power consumption for a given degreeof image sensor processing functionality.

An example integrated circuit system that can be used in combinationwith the above photodetectors, pixel regions and pixel circuits will nowbe described in connection with FIG. 18. FIG. 18 is a block diagram ofan image sensor integrated circuit (also referred to as an image sensorchip). The chip includes:

-   -   a pixel array (100) in which incident light is converted into        electronic signals, and in which electronic signals are        integrated into charge stores whose contents and voltage levels        are related to the integrated light incident over the frame        period;    -   row and column circuits (110 & 120) which are used to reset each        pixel, and read the signal related to the contents of each        charge store, in order to convey the information related to the        integrated light over each pixel over the frame period to the        outer periphery of the chip    -   analog circuits (130, 140, 150, 160, 230). The pixel electrical        signal from the column circuits is fed into the        analog-to-digital conver (160) where it is converted into a        digital number representing the light level at each pixel. The        pixel array and ADC are supported by analog circuits that        provide bias and reference levels (130, 140, & 150).    -   digital circuits (170, 180, 190, 200). The Image Enhancement        circuitry (170) provides image enhancement functions to the data        output from ADC to improve the signal to noise ratio. Line        buffer (180) temporarily stores several lines of the pixel        values to facilitate digital image processing and JO        functionality. (190) is a bank of registers that prescribe the        global operation of the system and/or the frame format. Block        200 controls the operation of the chip.    -   IO circuits (210 & 220) support both parallel input/output and        serial input/output. (210) is a parallel JO interface that        outputs every bit of a pixel value simultaneously. (220) is a        serial JO interface where every bit of a pixel value is output        sequentially.    -   a phase-locked loop (230) provides a clock to the whole chip.

In a particular example embodiment, when 0.11 μm CMOS technology node isemployed, the periodic repeat distance of pixels along the row-axis andalong the column-axis may be 700 nm, 900 nm, 1.1 μm, 1.2 μm, 1.4 μm,1.55 μm, 1.75 μm, 2.2 μm, or larger. The implementation of the smallestof these pixels sizes, especially 700 nm, 900 nm, 1.1 μm, and 1.2 μm,and 1.4 μm, may require transistor sharing among pairs or larger groupof adjacent pixels.

Very small pixels can be implemented in part because all of the siliconcircuit area associated with each pixel can be used for read-outelectronics since the optical sensing function is achieved separately,in another vertical level, by the optically-sensitive layer that residesabove the interconnect layer.

Because the optically sensitive layer and the read-out circuit thatreads a particular region of optically sensitive material exist onseparate planes in the integrated circuit, the shape (viewed from thetop) of (1) the pixel read-out circuit and (2) the optically sensitiveregion that is read by (1); can be generally different. For example itmay be desired to define an optically sensitive region corresponding toa pixel as a square; whereas the corresponding read-out circuit may bemost efficiently configured as a rectangle.

In an imaging array based on a top optically sensitive layer connectedthrough vias to the read-out circuit beneath, there exists no imperativefor the various layers of metal, vias, and interconnect dielectric to besubstantially or even partially optically transparent, although they maybe transparent in some embodiments. This contrasts with the case offront-side-illuminated CMOS image sensors in which a substantiallytransparent optical path must exist traversing the interconnect stack.In the case of conventional CMOS image sensors, this presents anadditional constraint in the routing of interconnect. This often reducesthe extent to which a transistor, or transistors, can practically beshared. For example, 4:1 sharing is often employed, but higher sharingratios are not. In contrast, a read-out circuit designed for use with atop-surface optically-sensitive layer can employ 8:1 and 16:1 sharing.

In embodiments, the optically sensitive layer may connect electricallyto the read-out circuit beneath without a metal intervening between theoptically sensitive layer and the read-out circuit beneath.

Embodiments of QD devices include a QD layer and a custom-designed orpre-fabricated electronic read-out integrated circuit. The QD layer isthen formed directly onto the custom-designed or pre-fabricatedelectronic read-out integrated circuit. In some embodiments, whereverthe QD layer overlies the circuit, it continuously overlaps and contactsat least some of the features of the circuit. In some embodiments, ifthe QD layer overlies three-dimensional features of the circuit, the QDlayer may conform to these features. In other words, there exists asubstantially contiguous interface between the QD layer and theunderlying electronic read-out integrated circuit. One or moreelectrodes in the circuit contact the QD layer and are capable ofrelaying information about the QD layer, e.g., an electronic signalrelated to the amount of radiation 1000 on the QD layer, to a readoutcircuit. The QD layer can be provided in a continuous manner to coverthe entire underlying circuit, such as a readout circuit, or patterned.If the QD layer is provided in a continuous manner, the fill factor canapproach about 100%, with patterning, the fill factor is reduced, butcan still be much greater than a typical 35% for some example CMOSsensors that use silicon photodiodes.

In embodiments, the QD optical devices are readily fabricated usingtechniques available in a facility normally used to make conventionalCMOS devices. For example, a layer of QDs can be solution-coated onto apre-fabricated electronic read-out circuit using, e.g., spin-coating,which is a standard CMOS process, and optionally further processed withother CMOS-compatible techniques to provide the final QD layer for usein the device. Because the QD layer need not require exotic or difficulttechniques to fabricate, but can instead be made using standard CMOSprocesses, the QD optical devices can be made in high volumes, and withno significant increase in capital cost (other than materials) overcurrent CMOS process steps.

FIG. 16C shows a two-row by three-column sub-region within a generallylarger array of top-surface electrodes. The array of electrical contactsprovides electrical communication to an overlying layer of opticallysensitive material. 1401 represents a common grid of electrodes used toprovide one shared contact to the optically sensitive layer. 1402represents the pixel-electrodes which provide the other contact forelectrical communication with the optically sensitive layer. Inembodiments, a voltage bias of −2 V may be applied to the common grid1401, and a voltage of +2.5 V may be applied at the beginning of eachintegration period to each pixel electrode 1402.

In embodiments, a direct non-metallic contact region (e.g., pn junctioncontact) may be used instead of a metal interconnect pixel electrode for1402.

Whereas the common contact 1401 is at a single electrical potentialacross the array at a given time, the pixel electrodes 1402 may vary intime and space across the array. For example if a circuit is configuredsuch that the bias at 1402 varies in relation to current flowing into orout of 1402, then different electrodes 1402 may be at different biasesthroughout the progress of the integration period. Region 1403represents the non-contacting region that lies between 1401 and 1402within the lateral plane. 1403 is generally an insulating material inorder to minimize dark current flowing between 1401 and 1402. 1401 and1402 may generally consist of different materials. Each may for examplebe chosen for example from the list: TiN; TiN/Al/TiN; Cu; TaN; Ni; Pt;and from the preceding list there may reside superimposed on one or bothcontacts a further layer or set of layers chosen from: Pt, alkanethiols,Pd, Ru, Au, ITO, or other conductive or partially conductive materials.

In example embodiments, the pixel electrodes 1402 may consist of asemiconductor, such as silicon, including p-type or n-type silicon,instead of a metal interconnect pixel electrode.

Embodiments described herein may be combined. Example embodimentsinclude a pixel circuit employing a pixel electrode that consists of asemiconductor, such as silicon, instead of a metal. In embodiments adirect connection between film and diode instead of metallic pixelelectrodes (either front side or back side) may be formed. Otherfeatures described herein may be used in combination with this approachor architecture.

In example embodiments using the above structures, interconnect 1452 mayform an electrode in electrical communication with a capacitance,impurity region on the semiconductor substrate or other charge store.

In embodiments, the charge store may be a pinned diode. In embodiments,the charge store may be a pinned diode in communication with anoptically sensitive material without an intervening metal being presentbetween the pinned diode and the optically sensitive layer.

In some embodiments, a voltage is applied to the charge store anddischarges due to the flow of current across the optically sensitivefilm over an integration period of time. At the end of the integrationperiod of time, the remaining voltage is sampled to generate a signalcorresponding to the intensity of light absorbed by the opticallysensitive layer during the integration period. In other embodiments, thepixel region may be biased to cause a voltage to accumulate in a chargestore over an integration period of time. At the end of the integrationperiod of time, the voltage may be sampled to generate a signalcorresponding to the intensity of light absorbed by the opticallysensitive layer during the integration period. In some exampleembodiments, the bias across the optically sensitive layer may vary overthe integration period of time due to the discharge or accumulation ofvoltage at the charge store. This, in turn, may cause the rate ofcurrent flow across the optically sensitive material to also vary overthe integration period of time. In addition, the optically sensitivematerial may be a nanocrystal material with photoconductive gain and therate of current flow may have a non-linear relationship with theintensity of light absorbed by the optically sensitive layer. As aresult, in some embodiments, circuitry may be used to convert thesignals from the pixel regions into digital pixel data that has a linearrelationship with the intensity of light absorbed by the pixel regionover the integration period of time. The non-linear properties of theoptically sensitive material can be used to provide a high dynamicrange, while circuitry can be used to linearize the signals after theyare read in order to provide digital pixel data. Example pixel circuitsfor read out of signals from pixel regions are described further below.

FIG. 16A represents closed—simple patterns 1430 (e.g., conceptualillustration) and 1432 (e.g., vias used to create photodetectorstructures). In the closed-simple illustrations 1430-1432 the positivelybiased electrical interconnect 1452 is provided in the center area of agrounded contained square electrical interconnect 1450. Squareelectrical interconnect 1450 may be grounded or may be at anotherreference potential to provide a bias across the optically sensitivematerial in the pixel region. For example, interconnect 1452 may bebiased with a positive voltage and interconnect may be biased with anegative voltage to provide a desired voltage drop across a nanocrystalmaterial in the pixel region between the electrodes. In thisconfiguration, when radiation 1000 to which the layer is responsivefalls within the square area a charge is developed and the charge isattracted to and move towards the center positively biased electricalinterconnect 1452. If these closed-simple patterns are replicated overan area of the layer, each closed simple pattern forms a portion or awhole pixel where they capture charge associated with incident radiation1000 that falls on the internal square area. In example embodiments, theelectrical interconnect 1450 may be part of a grid that forms a commonelectrode for an array of pixel regions. Each side of the interconnect1450 may be shared with the adjacent pixel region to form part of theelectrical interconnect around the adjacent pixel. In this embodiment,the voltage on this electrode may be the same for all of the pixelregions (or for sets of adjacent pixel regions) whereas the voltage onthe interconnect 1452 varies over an integration period of time based onthe light intensity absorbed by the optically sensitive material in thepixel region and can be read out to generate a pixel signal for eachpixel region. In example embodiments, interconnect 1450 may form aboundary around the electrical interconnect 1452 for each pixel region.The common electrode may be formed on the same layer as interconnect1452 and be positioned laterally around the interconnect 1450. In someembodiments, the grid may be formed above or below the layer ofoptically sensitive material in the pixel region, but the bias on theelectrode may still provide a boundary condition around the pixel regionto reduce cross over with adjacent pixel regions.

In embodiments, said optically sensitive material may be in directelectrical communication with a pixel electrode, charge store, or pinneddiode, without an intervening metal being present between said opticallysensitive material and said pixel electrode, charge store, or pinneddiode.

FIG. 16B illustrates open simple patterns of electrical interconnects.The open simple patterns do not, generally, form a closed pattern. Theopen simple pattern does not enclose a charge that is produced as theresult of incident radiation 1000 with the area between the positivelybiased electrical interconnect 1452 and the ground 1450; however, chargedeveloped within the area between the two electrical interconnects willbe attracted and move to the positively biased electrical interconnect1452. An array including separated open simple structures may provide acharge isolation system that may be used to identify a position ofincident radiation 1000 and therefore corresponding pixel assignment. Asabove, electrical interconnect 1450 may be grounded or be at some otherreference potential. In some embodiments, electrical interconnect 1450may be electrically connected with the corresponding electrode of otherpixels (for example, through underlying layers of interconnect) so thevoltage may be applied across the pixel array. In other embodiments, theinterconnect 1450 may extend linearly across multiple pixel regions toform a common electrode across a row or column.

Pixel circuitry that may be used to read out signals from the pixelregions will now be described. As described above, in embodiments, pixelstructures 1500 within the QDPC 100 of FIG. 14 may have pixel layouts1600, where pixel layouts 1600 may have a plurality of layoutconfigurations such as vertical, planar, diagonal, or the like. Pixelstructures 1500 may also have embedded pixel circuitry 1700. Pixelstructures may also be associated with the electrical interconnections1404 between the photodetector structures 1400 and pixel circuitry 1700.

In embodiments, quantum dot pixels 1800 within the QDPC 100 of FIG. 14may have pixel circuitry 1700 that may be embedded or specific to anindividual quantum dot pixel 1800, a group of quantum dot pixels 1800,all quantum dot pixels 1800 in an array of pixels, or the like.Different quantum dot pixels 1800 within the array of quantum dot pixels1800 may have different pixel circuitry 1700, or may have no individualpixel circuitry 1700 at all. In embodiments, the pixel circuitry 1700may provide a plurality of circuitry, such as for biasing, voltagebiasing, current biasing, charge transfer, amplifier, reset, sample andhold, address logic, decoder logic, memory, TRAM cells, flash memorycells, gain, analog summing, analog-to-digital conversion, resistancebridges, or the like. In embodiments, the pixel circuitry 1700 may havea plurality of functions, such as for readout, sampling, correlateddouble sampling, sub-frame sampling, timing, integration, summing, gaincontrol, automatic gain control, off-set adjustment, calibration, offsetadjustment, memory storage, frame buffering, dark current subtraction,binning, or the like. In embodiments, the pixel circuitry 1700 may haveelectrical connections to other circuitry within the QDPC 100, such aswherein other circuitry located in at least one of a second quantum dotpixel 1800, column circuitry, row circuitry, circuitry within thefunctional components 2004 of the QDPC 100, or other features 2204within the integrated system 2200 of the QDPC 100, or the like. Thedesign flexibility associated with pixel circuitry 1700 may provide fora wide range of product improvements and technological innovations.

Pixel circuitry 1700 within the quantum dot pixel 1800 may take aplurality of forms, ranging from no circuitry at all, justinterconnecting electrodes, to circuitry that provides functions such asbiasing, resetting, buffering, sampling, conversion, addressing, memory,and the like. In embodiments, electronics to condition or process theelectrical signal may be located and configured in a plurality of ways.For instance, amplification of the signal may be performed at eachpixel, group of pixels, at the end of each column or row, after thesignal has been transferred off the array, just prior to when the signalis to be transferred off the chip 2000, or the like. In anotherinstance, analog-to-digital conversion may be provided at each pixel,group of pixels, at the end of each column or row, within the chip's2000 functional components 2004, after the signal has been transferredoff the chip 2000, or the like. In addition, processing at any level maybe performed in steps, where a portion of the processing is performed inone location and a second portion of the processing is performed inanother location. An example may be the performing analog-to-digitalconversion in two steps, say with an analog combining at the pixel 1800and a higher-rate analog-to-digital conversion as a part of the chip's2000 functional components 2004.

In embodiments, different electronic configurations may requiredifferent levels of post-processing, such as to compensate for the factthat every pixel has its own calibration level associated with eachpixel's readout circuit. The QDPC 100 may be able to provide the readoutcircuitry at each pixel with calibration, gain-control, memoryfunctions, and the like. Because of the QDPC's 100 highly integratedstructure, circuitry at the quantum dot pixel 1800 and chip 2000 levelmay be available, which may enable the QDPC 100 to be an entire imagesensor system on a chip. In some embodiments, the QDPC 100 may also becomprised of a quantum dot material 200 in combination with conventionalsemiconductor technologies, such as CCD and CMOS.

Pixel circuitry may be defined to include components beginning at theelectrodes in contact with the quantum dot material 200 and ending whensignals or information is transferred from the pixel to other processingfacilities, such as the functional components 2004 of the underlyingchip 200 or another quantum dot pixel 1800. Beginning at the electrodeson the quantum dot material 200, the signal is translated or read. Inembodiments, the quantum dot material 200 may provide a change incurrent flow in response to radiation 1000. The quantum dot pixel 1800may require bias circuitry 1700 in order to produce a readable signal.This signal in turn may then be amplified and selected for readout.

In embodiments, the biasing of the photodetector may be time invariantor time varying. Varying space and time may reduce cross-talk, andenable a shrinking the quantum dot pixel 1800 to a smaller dimension,and require connections between quantum dot pixels 1800. Biasing couldbe implemented by grounding at the corner of a pixel 1800 and dots inthe middle. Biasing may occur only when performing a read, enablingeither no field on adjacent pixels 1800, forcing the same bias onadjacent pixels 1800, reading odd columns first then the even columns,and the like. Electrodes and/or biasing may also be shared betweenpixels 1800. Biasing may be implemented as a voltage source or as acurrent source. Voltage may be applied across a number of pixels, butthen sensed individually, or applied as a single large bias across astring of pixels 1800 on a diagonal. The current source may drive acurrent down a row, then read it off across the column. This mayincrease the level of current involved, which may decrease read noiselevels.

In embodiments, configuration of the field, by using a biasing scheme orconfiguration of voltage bias, may produce isolation between pixels.Currently may flow in each pixel so that only electron-hole pairsgenerated in that volume of pixel flow within that pixel. This may allowelectrostatically implemented inter-pixel isolation and cross-talkreduction, without physical separation. This could break the linkagebetween physical isolation and cross-talk reduction.

In embodiments, the pixel circuitry 1700 may include circuitry for pixelreadout. Pixel readout may involve circuitry that reads the signal fromthe quantum dot material 200 and transfers the signal to othercomponents 1900, chip functional components 2004, to the other features2204 of the integrated system 2200, or to other off-chip components.Pixel readout circuitry may include quantum dot material 200 interfacecircuitry, such as 3T and 4T circuits, for example. Pixel readout mayinvolve different ways to readout the pixel signal, ways to transformthe pixel signal, voltages applied, and the like. Pixel readout mayrequire a number of metal contacts with the quantum dot material 200,such as 2, 3, 4, 20, or the like. In embodiments, pixel readout mayinvolve direct electrical communication between the optically sensitivematerial and a pixel electrode, charge store, or pinned diode, withoutan intervening metal being present between said optically sensitivematerial and said pixel electrode, charge store, or pinned diode.

These electrical contacts may be custom configured for size, degree ofbarrier, capacitance, and the like, and may involve other electricalcomponents such a Schottky contact. Pixel readout time may be related tohow long the radiation 1000-induced electron-hole pair lasts, such asfor milliseconds or microseconds. In embodiments, this time my beassociated with quantum dot material 200 process steps, such as changingthe persistence, gain, dynamic range, noise efficiency, and the like.

The quantum dot pixels 1800 described herein can be arranged in a widevariety of pixel layouts 1600. Referring to FIGS. 17A through 17P forexample, a conventional pixel layout 1600, such as the Bayer filterlayout 1602, includes groupings of pixels disposed in a plane, whichdifferent pixels are sensitive to radiation 1000 of different colors. Inconventional image sensors, such as those used in most consumer digitalcameras, pixels are rendered sensitive to different colors of radiation1000 by the use of color filters that are disposed on top of anunderlying photodetector, so that the photodetector generates a signalin response to radiation 1000 of a particular range of frequencies, orcolor. In this configuration, mosaic of different color pixels isreferred to often as a color filter array, or color filter mosaic.Although different patterns can be used, the most typical pattern is theBayer filter pattern 1602 shown in FIG. 17A, where two green pixels, onered pixel and one blue pixel are used, with the green pixels (oftenreferred to as the luminance-sensitive elements) positioned on onediagonal of a square and the red and blue pixels (often referred to asthe chrominance-sensitive elements) are positioned on the otherdiagonal. The use of a second green pixel is used to mimic the humaneye's sensitivity to green light. Since the raw output of a sensor arrayin the Bayer pattern consists of a pattern of signals, each of whichcorresponds to only one color of light, demosaicing algorithms are usedto interpolate red, green and blue values for each point. Differentalgorithms result in varying quality of the end images. Algorithms maybe applied by computing elements on a camera or by separate imageprocessing systems located outside the camera. Quantum dot pixels may belaid out in a traditional color filter system pattern such as the BayerRGB pattern; however, other patterns may also be used that are bettersuited to transmitting a greater amount of light, such as Cyan, Magenta,Yellow (CMY). Red, Green, Blue (RGB) color filter systems are generallyknown to absorb more light than a CMY system. More advanced systems suchas RGB Cyan or RGB Clear can also be used in conjunction with Quantumdot pixels.

In one embodiment, the quantum dot pixels 1800 described herein areconfigured in a mosaic that imitates the Bayer pattern 1602; however,rather than using a color filter, the quantum dot pixels 1800 can beconfigured to respond to radiation 1000 of a selected color or group ofcolors, without the use of color filters. Thus, a Bayer pattern 1602under an embodiment includes a set of green-sensitive, red-sensitive andblue-sensitive quantum dot pixels 1800. Because, in embodiments, nofilter is used to filter out different colors of radiation 1000, theamount of radiation 1000 seen by each pixel is much higher.

The image sensor may detect a signal from the photosensitive material ineach of the pixel regions that varies based on the intensity of lightincident on the photosensitive material. In one example embodiment, thephotosensitive material is a continuous film of interconnectednanoparticles. Electrodes are used to apply a bias across each pixelarea. Pixel circuitry is used to integrate a signal in a charge storeover a period of time for each pixel region. The circuit stores anelectrical signal proportional to the intensity of light incident on theoptically sensitive layer during the integration period. The electricalsignal can then be read from the pixel circuitry and processed toconstruct a digital image corresponding to the light incident on thearray of pixel elements. In example embodiments, the pixel circuitry maybe formed on an integrated circuit device below the photosensitivematerial. For example, a nanocrystal photosensitive material may belayered over a CMOS integrated circuit device to form an image sensor.Metal contact layers from the CMOS integrated circuit may beelectrically connected to the electrodes that provide a bias across thepixel regions. U.S. patent application Ser. No. 12/106,256, entitled“Materials, Systems and Methods for Optoelectronic Devices,” filed Apr.18, 2008 (U.S. Published Patent Application No. 2009/0152664) includesadditional descriptions of optoelectronic devices, systems and materialsthat may be used in connection with example embodiments and is herebyincorporated herein by reference in its entirety. This is an exampleembodiment only and other embodiments may use different photodetectorsand photosensitive materials. For example, embodiments may use siliconor Gallium Arsenide (GaAs) photodetectors.

In example embodiments, an image sensor may be provided with a largenumber of pixel elements to provide high resolution. For example, anarray of 4, 6, 8, 12, 24 or more megapixels may be provided.

The use of such large numbers of pixel elements, combined with thedesirability of producing image sensor integrated circuits having smallareas such as diagonal dimensions of order ⅓ inch or ¼ inch, entails theuse of small individual pixels. Desirable pixel geometries include, forexample, 1.75 μm linear side dimensions, 1.4 μm linear side dimensions,1.1 μm linear side dimensions, 0.9 μm linear side dimensions, 0.8 μmlinear side dimensions, and 0.7 μm linear side dimensions.

Embodiments include systems that enable a large fill factor by ensuringthat 100%, or nearly 100%, of the area of each pixel includes anoptically sensitive material on which incident light of interest inimaging is substantially absorbed. Embodiments include imaging systemsthat provide a large chief ray acceptance angle. Embodiments includeimaging systems that do not required microlenses. Embodiments includeimaging systems that are less sensitive to the specific placement ofmicrolenses (microlens shift) in view of their increased fill factor.Embodiments include highly sensitive image sensors. Embodiments includeimaging systems in which a first layer proximate the side of opticalincidence substantially absorbs incident light; and in which asemiconductor circuit that may included transistors carriers outelectronic read-out functions.

Embodiments include optically sensitive materials in which theabsorption is strong, i.e., the absorption length is short, such as anabsorption length (1/alpha) less than 1 um. Embodiments include imagesensor comprising optically sensitive materials in which substantiallyall light across the visible wavelength spectrum, including out to thered ˜630 nm, is absorbed in a thickness of optically sensitive materialless than approximately 1 micrometer.

Embodiments include image sensors in which the lateral spatialdimensions of the pixels are approximately 2.2 μm, 1.75 μm, 1.55 μm, 1.4μm, 1.1 μm, 900 nm, 700 nm, 500 nm; and in which the optically sensitivelayer is less than 1 μm and is substantially absorbing of light acrossthe spectral range of interest (such as the visible in exampleembodiments); and in which crosstalk (combined optical and electrical)among adjacent pixels is less than 30%, less than 20%, less than 15%,less than 10%, or less than 5%.

Embodiments include pixel circuits, functioning in combination with anoptically sensitive material, in which at least one of dark current,noise, photoresponse nonuniformity, and dark current nonuniformity areminimized through the means of integrating the optically sensitivematerial with the pixel circuit.

Embodiments include integration and processing approaches that areachieved at low additional cost to manufacture, and can be achieved (orsubstantially or partially achieved) within a CMOS silicon fabricationfoundry.

FIG. 19A depicts a front-side illuminated CMOS image sensor pixel inwhich an optically sensitive material has been integrated in intimatecontact with the silicon diode. 601 depicts a silicon substrate on whichthe image sensor is fabricated. 603 depicts a diode formed in silicon.605 is the metal interconnect and 607 is the interlayer dielectric stackthat serves to provide communication of electrical signals within andacross the integrated circuit. 609 is an optically sensitive materialthat is the primary location for the absorption of light to be imaged.611 is a transparent electrode that is used to provide electricalbiasing of the optically sensitive material to enable photocarriercollection from it. 613 is a passivation layer that may consist of atleast one of an organic or polymer encapsulant (such as parylene) or aninorganic such as Si3N4 or a stack incorporating combinations thereof.613 serves to protect the underlying materials and circuits fromenvironmental influences such as the impact of water or oxygen. 615 is acolor filter array layer that is a spectrally-selective transmitter oflight used in aid of achieving color imaging. 617 is a microlens thataids in the focusing of light onto 609 the optically sensitive material.

Referring to FIG. 19A, in embodiments, photocurrent generated in 609 theoptically sensitive material due to illumination may be transferred,with high efficiency, from the sensitizing material 609 to the diode‘2.’ Since most incident photons will be absorbed by the sensitizingmaterial ‘5’, the diode 603 no longer needs serve the predominantphotodetection role. Instead its principal function is to serve as diodethat enables maximal charge transfer and minimal dark current.

Referring to FIG. 19A, the diode 603 may be pinned using the sensitizingmaterial 609 at its surface. The thickness of the sensitizing material609 may be approximately 500 nm, and may range from 100 nm to 5 um. Inembodiments, a p-type sensitizing material 609 may be employed for thelight conversion operation and for depleting an n-type silicon diode603. The junction between the sensitizing material 609 and the silicondiode 603 may be termed a p-n heterojunction in this example.

Referring to FIG. 19A, in the absence of an electrical bias, the n-typesilicon 603 and p-type sensitizing material 609 reach equilibrium, i.e.,their Fermi levels come into alignment. In an example embodiment, theresultant band-bending produce a built-in potential in the p-typesensitizing material 609 such that a depletion region is formed therein.Upon the application of an appropriate bias within the silicon circuitry(this potential difference applied, for example, via the differencebetween 611 and 603 in FIG. 19A), the amplitude of this potential isaugmented by an applied potential, resulting in a deepening of thedepletion region that reaches into the p-type sensitizing material 609.The resultant electrical field results in the extraction ofphotoelectrons from the sensitizing material 609 into the n+ siliconlayer 603. Biasing and doping in the silicon 603 achieve the collectionof the photoelectrons from the sensitizing layer 609, and can achievefully depletion of the n-type silicon 603 under normal bias (such as 3V, with a normal range of 1V to 5V). Holes are extracted through asecond contact (such as 611 in FIG. 19A) to the sensitizing layer 609.

Referring to FIG. 19A, in the case of a vertical device, the contact 611may be formed atop the sensitizing material 609.

FIG. 19B depicts a front-side illuminated CMOS image sensor pixel inwhich an optically sensitive material has been integrated in intimatecontact with the silicon diode. 631 depicts a silicon substrate on whichthe image sensor is fabricated. 633 depicts a diode formed in silicon.639 is the metal interconnect and 637 the interlayer dielectric stackthat serves to provide communication of electrical signals within andacross the integrated circuit. 641 is an optically sensitive materialthat is the primary location for the absorption of light to be imaged.643 is a transparent electrode that is used to provide electricalbiasing of the optically sensitive material to enable photocarriercollection from it. 645 is a passivation layer that may consist of atleast one of an organic or polymer encapsulant (such as parylene) or aninorganic such as Si3N4 or a stack incorporating combinations thereof.645 serves to protect the underlying materials and circuits fromenvironmental influences such as the impact of water or oxygen. 647 is acolor filter array layer that is a spectrally-selective transmitter oflight used in aid of achieving color imaging. 649 is a microlens thataids in the focusing of light onto 641 the optically sensitive material.635 is a material that resides between the optically sensitive material641 and the diode 633. 635 may be referred to as an added pinning layer.Example embodiments include a p-type silicon layer. Example embodimentsinclude a non-metallic material such as a semiconductor and/or it couldinclude polymer and/or organic materials. In embodiments, material 635may provide a path having sufficient conductivity for charge to flowfrom the optically sensitive material to the diode, but would not bemetallic interconnect. In embodiments, 635 serves to passivate thesurface of the diode and create the pinned diode in this exampleembodiment (instead of the optically sensitive material, which would beon top of this additional layer).

Referring to FIG. 19C, a substantially lateral device may be formedwherein an electrode atop the silicon 661 that resides beneath thesensitizing material 659 may be employed. In embodiments, the electrode661 may be formed using metals or other conductors such as TiN, TiOxNy,Al, Cu, Ni, Mo, Pt, PtSi, or ITO.

Referring to FIG. 19C, a substantially lateral device may be formedwherein the p-doped silicon 661 that resides beneath the sensitizingmaterial 659 may be employed for biasing.

Example embodiments provide image sensors that use an array of pixelelements to detect an image. The pixel elements may includephotosensitive material, also referred to herein as the sensitizingmaterial, corresponding to 609 in FIG. 19A, 641 in FIG. 19B, 659 in FIG.19C, 709 in FIG. 19A, the filled ellipse in FIG. 21 on which light 801is incident, 903 in FIG. 22, 1003 in FIG. 23, and 1103 in FIGS. 24Athrough 24F.

FIG. 19C depicts a front-side illuminated CMOS image sensor pixel inwhich an optically sensitive material has been integrated in intimatecontact with the silicon diode. In this embodiment the opticallysensitive material is biased by the silicon substrate directly; as aresult, in this embodiment, no transparent electrode is required on top.651 depicts a silicon substrate on which the image sensor is fabricated.653 depicts a diode formed in silicon. 655 is the metal interconnect and657 the interlayer dielectric stack that serves to provide communicationof electrical signals within and across the integrated circuit. 659 isan optically sensitive material that is the primary location for theabsorption of light to be imaged. 661 points to an example region of thesilicon substrate 651 that is used to provide electrical biasing of theoptically sensitive material to enable photocarrier collection from it.663 is a passivation layer that may consist of at least one of anorganic or polymer encapsulant (such as parylene) or an inorganic suchas Si3N4 or a stack incorporating combinations thereof. 663 serves toprotect the underlying materials and circuits from environmentalinfluences such as the impact of water or oxygen. 665 is a color filterarray layer that is a spectrally-selective transmitter of light used inaid of achieving color imaging. 667 is a microlens that aids in thefocusing of light onto 659 the optically sensitive material.

FIG. 20A depicts a cross-section of a back-side illuminated CMOS imagesensor pixel in which an optically sensitive material has beenintegrated in intimate contact with the silicon photodiode. 705 depictsa silicon substrate on which the image sensor is fabricated. 707 depictsa diode formed in silicon. 703 is the metal interconnect and 701 theinterlayer dielectric stack that serves to provide communication ofelectrical signals within and across the integrated circuit. 709 is anoptically sensitive material that is the primary location for theabsorption of light to be imaged. 711 is a transparent electrode that isused to provide electrical biasing of the optically sensitive materialto enable photocarrier collection from it. 713 is a passivation layerthat may consist of at least one of an organic or polymer encapsulant(such as parylene) or an inorganic such as Si3N4 or a stackincorporating combinations thereof. 713 serves to protect the underlyingmaterials and circuits from environmental influences such as the impactof water or oxygen. 715 is a color filter array layer that is aspectrally-selective transmitter of light used in aid of achieving colorimaging. 717 is a microlens that aids in the focusing of light onto 709the optically sensitive material.

FIG. 20B depicts a cross-section of a back-side illuminated CMOS imagesensor pixel in which an optically sensitive material has beenintegrated in intimate contact with the silicon photodiode. 735 depictsa silicon substrate on which the image sensor is fabricated. 737 depictsa diode formed in silicon. 733 is the metal interconnect and 731 theinterlayer dielectric stack that serves to provide communication ofelectrical signals within and across the integrated circuit. 741 is anoptically sensitive material that is the primary location for theabsorption of light to be imaged. 743 is a transparent electrode that isused to provide electrical biasing of the optically sensitive materialto enable photocarrier collection from it. 745 is a passivation layerthat may consist of at least one of an organic or polymer encapsulant(such as parylene) or an inorganic such as Si3N4 or a stackincorporating combinations thereof. 745 serves to protect the underlyingmaterials and circuits from environmental influences such as the impactof water or oxygen. 747 is a color filter array layer that is aspectrally-selective transmitter of light used in aid of achieving colorimaging. 749 is a microlens that aids in the focusing of light onto ‘5’the optically sensitive material. 739 is a material that resides betweenthe optically sensitive material 741 and the diode 737. 739 may bereferred to as an added pinning layer. Example embodiments include ap-type silicon layer. Example embodiments include a non-metallicmaterial such as a semiconductor and/or it could include polymer and/ororganic materials. In embodiments, material 739 may provide a pathhaving sufficient conductivity for charge to flow from the opticallysensitive material to the diode, but would not be metallic interconnect.In embodiments, 739 serves to passivate the surface of the diode andcreate the pinned diode in this example embodiment (instead of theoptically sensitive material, which would be on top of this additionallayer).

FIG. 21 is a circuit diagram for a back-side illuminated image sensor inwhich optically sensitive material is integrated to silicon chip fromthe back side. 801 depicts light illuminating the optically sensitivematerial (filled circle with downward-pointing arrow). 803 is anelectrode that provides bias across the optically sensitive material. Itcorresponds to the top transparent electrode (711 of FIG. 20A) or to theregion of the silicon substrate used to provide electrical biasing (743of FIG. 20B). 805 is the silicon diode (corresponding to 603, 633,653,707, and 737 in FIGS. 6A, 6B, 6C, 7A, and 7B, respectively). 805 mayalso be termed the charge store. 805 may be termed the pinned diode. 807is an electrode on the front side of silicon (metal), which ties totransistor gate of M1. 809 is the transistor M1, which separates thediode from sense node and the rest of the readout circuitry. The gate ofthis transistor is 807. A transfer signal is applied to this gate totransfer charge between the diode and the sense node 811. 811 is thesense node. It is separated from diode, allowing flexibility in thereadout scheme. 813 is an electrode on the front side of silicon(metal), which ties to the transistor gate of M2. 815 is an electrode onthe front side of silicon (metal), which ties to transistor drain of M2.815 may be termed a reference potential. 815 can provide VDD for reset.817 is the transistor M2, which acts as a reset device. It is used toinitialize the sense node before readout. It is also used to initializethe diode before integration (when M1 and M2 are both turned on). Thegate of this transistor is 813. A reset signal is applied to this gateto reset the sense node 811. 819 is transistor M3, which is used to readout the sense node voltage. 821 is transistor M4, which is used toconnect the pixel to the readout bus. 823 is an electrode on the frontside of silicon (metal), which ties to the gate of M4. When it is high,the pixel driving the readout bus vcol. 825 is the readout bus vcol. 801and 803 and 805 reside within the backside of silicon. 807-825 residewithin the frontside of silicon, including metal stack and transistors.

Referring to FIG. 21, the diagonal line is included to help describe thebackside implementation. The transistors to the right of this line wouldbe formed on the front side. The diode and optically sensitive materialon the left would be on the back side. The diode would extend from theback side through the substrate and near to the front side. This allowsa connection to be formed between the transistors on the front side totransfer charge from the diode to the sense node 811 of the pixelcircuit.

Referring to FIG. 21, the pixel circuit may be defined as the set of allcircuit elements in the figure, with the exception of the opticallysensitive material. The pixel circuit includes the read-out circuit, thelatter include a source follower transistor 819, row select transistor821 with row select gate 823, and column read out 825.

Referring to FIG. 25, in embodiments, the pixel circuit may operate inthe following manner.

A first reset (FIG. 25 at “A”) is performed to reset the sense node (811from FIG. 21) and the diode (805 from FIG. 21) prior to integration.Reset transistor (817 from FIG. 21) and charge transfer transistor (809from FIG. 21) are open during the first reset. This resets the sensenode (811 from FIG. 21) to the reference potential (for example 3Volts). The diode is pinned to a fixed voltage when it is depleted. Saidfixed voltage to which the diode is pinned may be termed the depletionvoltage of the diode. The reset depletes the diode which resets itsvoltage (for example to 1 Volt). Since it is pinned, it will not reachthe same voltage level as the sense node.

The charge transfer transistor (809 from FIG. 21) is then closed (FIG.25 at “B”) to start the integration period which isolates the sense nodefrom the diode.

Charge is integrated (FIG. 25 at “C”) from the optically sensitivematerial into the diode during the integration period of time. Theelectrode that biases the optically sensitive film is at a lower voltagethan the diode (for example 0 Volts) so there is a voltage differenceacross the material and charge integrates to the diode. The charge isintegrated through a non-metallic contact region between the materialand the diode. In embodiments, this is the junction between theoptically sensitive material and the n-doped region of the diode. Inembodiments, there may reside other non-metallic layers (such as p-typesilicon) between the optically sensitive material and the diode. Theinterface with the optically sensitive material causes the diode to bepinned and also passivates the surface of the n-doped region byproviding a hole accumulation layer. This reduces noise and dark currentthat would otherwise be generated by silicon oxide formed on the topsurface of the diode.

After the integration period, a second reset (FIG. 25 at “D”) of thesense node occurs immediately prior to read out (the reset transistor isturned on while the diode remains isolated). This provides a knownstarting voltage for read out and eliminates noise/leakage introduced tothe sense node during the integration period. The double reset processfor pixel read out is referred to as true correlated double sampling.

The reset transistor is then closed and the charge transfer transistoris opened (FIG. 25 at “E”) to transfer charge from the diode to thesense node which is then read out through the source follower and columnline.

Referring to FIG. 19A, the use of the sensitizing material 609 mayprovide shorter absorption length than silicon's across the spectrarange of interest. The sensitizing material may provide absorptionlengths of 1 μm and shorter.

Referring to FIG. 19A, the high efficiency of photocarrier transfer fromthe sensitizing material 609 to a read-out integrated circuit beneathvia diode 603 may be achieved.

Referring FIG. 19A, the system described may achieve a minimum of darkcurrent and/or noise and/or photoresponse nonuniformity and/or darkcurrent nonuniformity by integrating the optically sensitive material609 with the silicon read-out circuit via diode 603.

Referring to FIG. 19A, examples of optically sensitive material 609include dense thin films made of colloidal quantum dots. Constituentmaterials include PbS, PbSe, PbTe; CdS, CdSe, CdTe; Bi₂S₃, In₂S₃,In₂Se₃; SnS, SnSe, SnTe; ZnS, ZnSe, ZnTe. The nanoparticles may be inthe range of 1 nm to 10 nm in diameter, and may be substantiallymonodispersed, i.e., may possess substantially the same size and shape.The materials may include organic ligands and/or crosslinkers to aid insurface passivation and of a length and conductivity that, combined,facilitate inter-quantum-dot charge transfer.

Referring to FIG. 19A, examples of optically sensitive material 609include thin films made of organic materials that are stronglyabsorptive of light in some or all wavelength ranges of interest.Constituent materials include P3HT, PCBM, PPV, MEH-PPV, and copperphthalocyanine and related metal phthalocyanines.

Referring to FIG. 19A, examples of optically sensitive material 609include thin films made of inorganic materials such as CdTe, copperindium gallium (di)selenide (CIGS), Cu₂ZnSnS₄ (CZTS), or III-V typematerials such as AlGaAs.

Referring to FIG. 19A, optically sensitive material 609 may be directlyintegrated with a diode 603 in a manner that may, among other benefits,reduce dark currents. The direct integration of the optically sensitivematerial 609 with the silicon diode 603 may lead to reduced darkcurrents associated with interface traps located on the surface of adiode. This concept may enable substantially complete transfer of chargefrom the diode into a floating sense node, enabling true correlateddouble sample operation.

Referring to FIGS. 19A, 19B, and 19C, the respective sensitizingmaterials 609, 641, and 659 may be integrated with, and serve to augmentthe sensitivity and reduce the crosstalk of, a front-side-illuminatedimage sensor. Electrical connection is made between the sensitizingmaterial 609, 641, and 659 and the respective diode 603, 633, and 653.

Referring to FIGS. 20A and 20B, the respective sensitizing materials 709and 741 may be integrated with, and serve to augment the sensitivity andreduce the crosstalk of, a back-side-illuminated image sensor. Followingthe application and thinning of the second wafer atop a first, plus anyfurther implants and surface treatments, a substantially planar siliconsurface is presented. With this material may be integrated thesensitizing material materials 709 and 741.

The electrical biasing of the sensitizing material may be achievedsubstantially in the lateral or in the vertical direction.

Referring to FIG. 19A, which may be termed a substantially verticalbiasing case, bias across the sensitizing material 609 is providedbetween the diode 603 and a top electrode 611. In this case the topelectrode 611 is desired to be substantially transparent to thewavelengths of light to be sensed. Examples of materials that can beused to form top electrode 611 include MoO3, ITO, AZO, organic materialssuch as BPhen, and very thin layers of metals such as aluminum, silver,copper, nickel, etc.

Referring to FIG. 19B, which may be termed a substantially lateral, orcoplanar, biasing case, bias across the sensitizing material 641 isprovided between the diode 633 and silicon substrate electrode 639.

Referring to FIG. 19C, which may be termed partially lateral, partiallyvertical, biasing case, bias across the sensitizing material 659 isprovided between the diode 653 and electrode 661.

FIG. 22 depicts an image sensor device in cross-section. 901 is thesubstrate and may also include circuitry and metal and interlayerdielectric and top metal. 903 is a continuous photosensitive materialthat is contacted using metal in 901 and possibly in 905. 905 istransparent, or partially-transparent, or wavelength-selectivelytransparent, material on top of 903. 907 is an opaque material thatensures that light incident from the top of the device, and arriving ata non-normal angle of incidence onto region 905, is not transferred toadjacent pixels such as 909, a process that would, if it occurred, beknown as optical crosstalk.

FIG. 23 depicts an image sensor device in cross-section. 1001 is thesubstrate and may also include circuitry and metal and interlayerdielectric and top metal. 1003 is a photosensitive material that iscontacted using metal in 1001 and possibly in 1005. 1005 is transparent,or partially-transparent, or wavelength-selectively transparent,material on top of 1003. 1007 is an opaque material that ensures thatlight incident from the top of the device, and arriving at a non-normalangle of incidence onto region 1005 and thence to 1003, is nottransferred to adjacent pixels such as 1009 or 1011, a process thatwould, if it occurred, be known as optical or electrical or optical andelectrical crosstalk.

FIGS. 24A through 24F depict in cross-section a means of fabricating anoptical-crosstalk-reducing structure such as that shown in FIG. 22. FIG.24A depicts a substrate 1101 onto which is deposited an opticallysensitive material 1103 and an ensuing layer or layers 1105 including asexamples encapsulant, passivation material, dielectric, color filterarray, microlens material, as examples. In FIG. 24B, layer 1105 has beenpatterned and etched in order to define pixellated regions. In FIG. 24C,a blanket of metal 1107 has been deposited over the structure shown inFIG. 24B. In FIG. 24D, the structure of FIG. 24C has been directionallyetched such as to remove regions of metal from 1107 on horizontalsurfaces, but leave it on vertical surfaces. The resulting verticalmetal layers will provide light obscuring among adjacent pixels in thefinal structure. In FIG. 24E a furtherpassivation/encapsulation/color/microlens layer or layers have beendeposited 1109. In FIG. 24F, the structure has been planarized.

Referring again to FIG. 22, optical cross-talk between pixels may bereduced by deposition of a thin layer 907 (e.g., 10 nm to 20 nmdepending on material) of a reflective material on a sidewall of therecess of the passivation layer between photosensitive layer 903 andcolor filter array (top portion of 905). Since the layer 905 isdeposited on the sidewall, its minimum thickness is defined only byoptical properties of the material, not by minimum critical dimension ofthe lithography process used.

In embodiments, a thin (e.g., 5 nm to 10 nm) dielectric transparent etchstop layer is deposited as a blanket film over an optically sensitivematerial. A thicker (e.g., 50 nm to 200 nm) also transparent dielectricpassivation layer (SiO₂) is deposited over an etch stop layer. Thecheckerboard pattern the size of the pixel per unit is etched, the 10 nmaluminum metal layer is deposited over the topography using a conformalprocess (e.g., CVD, PECVD, ALD) and metal is removed from the bottom ofthe recessed parts of the pattern using directional (anisotropic)reactive ion plasma etch process. The recessed areas are filled with thesame transparent passivation dielectric (SiO₂) and overfilled to providesufficiently thick film to allow a planarization process, for example,either using Chemical Mechanical Polishing or Back Etch. Said processesremove excess SiO₂ and also residual metal film over horizontalsurfaces. Similar processes can be applied for isolation of CFA ormicrolens layers.

Referring to FIG. 22, a vertical metal layer 907 may provide improvedoptical isolation between small pixels without substantial photoresponseloss.

Referring to FIG. 23, for optical isolation of pixels through theoptically sensitive material 1003, the following structure and processmay be employed. A hard mask protective pattern is formed on the surfaceof optically sensitive material using high-resolution lithographytechniques such as double-exposure or imprint technology. The mask formsa grid with the minimum dimensions (for example, 22 nm or 16 nm width).Exposed photosensitive material is etched using anisotropic reactive ionplasma etch process thru all or a major part of the photosensitivelayer. The formed recess is filled with, for example, a) one or moredielectric materials with the required refractive index to providecomplete internal reflection of photons back into the pixel or b)exposed photosensitive material is oxidized to form an electricalisolation layer about 1-5 nm thick on sidewalls of the recess and theremaining free space is filled with the reflective metal material suchas aluminum using, for example, conventional vacuum metallizationprocesses. The residual metal on the surface of photosensitive materialis removed either by wet or dry etching or by mechanical polishing.

Pixel circuitry may be defined to include components beginning at theelectrodes in contact with the quantum dot material 200 and ending whensignals or information is transferred from the pixel to other processingfacilities, such as the functional components 2004 of the underlyingchip 200 or another quantum dot pixel 1800. Beginning at the electrodeson the quantum dot material 200, the signal is translated or read. Inembodiments, the quantum dot material 200 may provide a change incurrent flow in response to radiation 1000. The quantum dot pixel 1800may require bias circuitry 1700 in order to produce a readable signal.This signal in turn may then be amplified and selected for readout. Oneembodiment of a pixel circuit shown in FIG. 26 uses a reset-biastransistor 1802, amplifier transistor 1804, and column addresstransistor 1808. This three-transistor circuit configuration may also bereferred to as a 3T circuit. Here, the reset-bias transistor 1802connects the bias voltage 1702 to the photoconductive photovoltaicquantum dot material 200 when reset 1704 is asserted, thus resetting theelectrical state of the quantum dot material 200. After reset 1704, thequantum dot material 200 may be exposed to radiation 1000, resulting ina change in the electrical state of the quantum dot material 200, inthis instance a change in voltage leading into the gate of the amplifier1804. This voltage is then boosted by the amplifier transistor 1804 andpresented to the address selection transistor 1808, which then appearsat the column output of the address selection transistor 1808 whenselected. In some embodiments, additional circuitry may be added to thepixel circuit to help subtract out dark signal contributions. In otherembodiments, adjustments for dark signal can be made after the signal isread out of the pixel circuit. In example, embodiments, additionalcircuitry may be added for film binning or circuit binning.

FIG. 27 shows an embodiment of a single-plane computing device 100 thatmay be used in computing, communication, gaming, interfacing, and so on.The single-plane computing device 100 is shown to include a peripheralregion 101 and a display region 103. A touch-based interface device 117,such as a button or touchpad, may be used in interacting with thesingle-plane computing device 100.

An example of a first camera module 113 is shown to be situated withinthe peripheral region 101 of the single-plane computing device 100 andis described in further detail, below. Example light sensors 115A, 115Bare also shown to be situated within the peripheral region 101 of thesingle-plane computing device 100 and are described in further detail,below, with reference to FIG. 30. An example of a second camera module105 is shown to be situated in the display region 103 of thesingle-plane computing device 100 and is described in further detail,below, with reference to FIG. 29.

Examples of light sensors 107A, 107B, shown to be situated in thedisplay region 103 of the single-plane computing device 100 and aredescribed in further detail, below, with reference to FIG. 30. Anexample of a first source of optical illumination 111 (which may bestructured or unstructured) is shown to be situated within theperipheral region 101 of the single-plane computing device 100. Anexample of a second source of optical illumination 109 is shown to besituated in the display region 103.

In embodiments, the display region 103 may be a touchscreen display. Inembodiments, the single-plane computing device 100 may be a tabletcomputer. In embodiments, the single-plane computing device 100 may be amobile handset.

FIG. 28 shows an embodiment of a double-plane computing device 200 thatmay be used in computing, communication, gaming, interfacing, and so on.The double-plane computing device 200 is shown to include a firstperipheral region 201A and a first display region 203A of a first plane210, a second peripheral region 201B and a second display region 203B ofa second plane 230, a first touch-based interface device 217A of thefirst plane 210 and a second touch-based interface device 217B of thesecond plane 230. The example touch-based interface devices 217A, 217Bmay be buttons or touchpads that may be used in interacting with thedouble-plane computing device 200. The second display region 203B mayalso be an input region in various embodiments.

The double-plane computing device 200 is also shown to include examplesof a first camera module 213A in the first peripheral region 201A and asecond camera module 213B in the second peripheral region 201B. Thecamera modules 213A, 213B are described in more detail, below, withreference to FIG. 29. As shown, the camera modules 213A, 213B aresituated within the peripheral regions 201A, 201B of the double-planecomputing device 200. Although a total of two camera modules are shown,a person of ordinary skill in the art will recognize that more or fewerlight sensors may be employed.

A number of examples of light sensors 215A, 215B, 215C, 215D, are shownsituated within the peripheral regions 201A, 201B of the double-planecomputing device 200. Although a total of four light sensors are shown,a person of ordinary skill in the art will recognize that more or fewerlight sensors may be employed. Examples of the light sensors 215A, 215B,215C, 215D, are described, below, in further detail with reference toFIG. 4. As shown, the light sensors 215A, 215B, 215C, 215D, are situatedwithin the peripheral regions 201A, 201B of the double-plane computingdevice 200.

The double-plane computing device 200 is also shown to include examplesof a first camera module 205A in the first display region 203A and asecond camera module 205B in the second display region 203B. The cameramodules 205A, 205B are described in more detail, below, with referenceto FIG. 29. As shown, the camera modules 205A, 205B are situated withinthe display regions 203A, 203B of the double-plane computing device 200.Also shown as being situated within the display regions 203A, 203B ofthe double-plane computing device 200 are examples of light sensors207A, 207B, 207C, 207D. Although a total of four light sensors areshown, a person of ordinary skill in the art will recognize that more orfewer light sensors may be employed. Examples of the light sensors 207A,207B, 207C, 207D are described, below, in further detail with referenceto FIG. 30. Example sources of optical illumination 211A, 211B are shownsituated within the peripheral region 201A, 201B and other examplesources of optical illumination 209A, 209B are shown situated within oneof the display regions 203A, 203B and are also described with referenceto FIG. 30, below. A person of ordinary skill in the art will recognizethat various numbers and locations of the described elements, other thanthose shown or described, may be implemented.

In embodiments, the double-plane computing device 200 may be a laptopcomputer. In embodiments, the double-plane computing device 200 may be amobile handset.

With reference now to FIG. 29, an embodiment of a camera module 300 thatmay be used with the computing devices of FIG. 27 or FIG. 28 is shown.The camera module 300 may correspond to the camera module 113 of FIG. 27or the camera modules 213A, 213B of FIG. 28. As shown in FIG. 29, thecamera module 300 includes a substrate 301, an image sensor 303, andbond wires 305. A holder 307 is positioned above the substrate. Anoptical filter 309 is shown mounted to a portion of the holder 307. Abarrel 311 holds a lens 313 or a system of lenses.

FIG. 30 shows an embodiment of a light sensor 400 that may be used withthe computing devices of FIG. 27 or FIG. 28 an example embodiment of alight sensor. The light sensor 400 may correspond to the light sensors115A, 115B of FIG. 27 of the light sensors 215A, 215B, 215C, 215D ofFIG. 28. The light sensor 400 is shown to include a substrate 401, whichmay correspond to a portion of either or both of the peripheral region101 or the display region 103 of FIG. 27. The substrate 401 may alsocorrespond to a portion of either or both of the peripheral regions201A, 201B or the display regions 203A, 203B of FIG. 28. The lightsensor 400 is also shown to include electrodes 403A, 403B used toprovide a bias across light-absorbing material 405 and to collectphotoelectrons therefrom. An encapsulation material 407 or a stack ofencapsulation materials is shown over the light-absorbing material 405.Optionally, the encapsulation material 407 may include conductiveencapsulation material for biasing and/or collecting photoelectrons fromthe light-absorbing material 405.

Elements of a either the single-plane computing device 100 of FIG. 27,or the double-plane computing device 200 of FIG. 28, may be connected orotherwise coupled with one another. Embodiments of the computing devicesmay include a processor. It may include functional blocks, and/orphysically distinct components, that achieve computing, imageprocessing, digital signal processing, storage of data, communication ofdata (through wired or wireless connections), the provision of power todevices, and control of devices. Devices that are in communication withthe processor include devices of FIG. 27 may include the display region103, the touch-based interface device 117, the camera modules 105, 113,the light sensors 115A, 115B, 107A, 107B, and the sources of opticalillumination 109, 111. Similarly correspondences may apply to FIG. 28 aswell.

The light sensor of FIG. 30 may include a light-absorbing material 405of various designs and compositions. In embodiments, the light-absorbingmaterial may be designed to have an absorbance that is sufficientlysmall, across the visible wavelength region approximately 450 nm to 650nm, such that, in cases in which the light sensor of FIG. 30 isincorporated into the display region of a computing device, only amodest fraction of visible light incident upon the sensor is absorbed bythe light-absorbing material. In this case, the quality of the imagesdisplayed using the display region is not substantially compromised bythe incorporation of the light-absorbing material along the optical pathof the display. In embodiments, the light-absorbing material 405 mayabsorb less than 30%, or less than 20%, or less than 10%, of lightimpinging upon it in across the visible spectral region.

In embodiments, the electrodes 403A, 403B, and, in the case of aconductive encapsulant for 407, the top electrode 407, may beconstituted using materials that are substantially transparent acrossthe visible wavelength region approximately 450 nm to 650 nm. In thiscase, the quality of the images displayed using the display region isnot substantially compromised by the incorporation of thelight-absorbing material along the optical path of the display.

In embodiments, the light sensor of FIG. 30 may include a light-sensingmaterial capable of sensing infrared light. In embodiments, thelight-sensing material may be a semiconductor having a bandgapcorresponding to an infrared energy, such as in the range 0.5 eV-1.9 eV.In embodiments, the light-sensing material may have measurableabsorption in the infrared spectral range; and may have measurableabsorption also in the visible range. In embodiments, the light-sensingmaterial may absorb a higher absorbance in the visible spectral range asin the infrared spectral range; yet may nevertheless be used to sensegesture-related signals in the infrared spectral range.

In an example embodiment, the absorbance of the light-sensingdisplay-incorporated material may lie in the range 2-20% in the visible;and may lie in the range 0.1-5% in the infrared. In an exampleembodiment, the presence of visible light in the ambient, and/or emittedfrom the display, may produce a background signal within the lightsensor, as a consequence of the material visible-wavelength absorptionwithin the light-absorbing material of the light sensor. In an exampleembodiment, sensing in the infrared region may also be achieved. Thelight sources used in aid of gesture recognition may be modulated usingspatial, or temporal, codes, allowing them to be distinguished from thevisible-wavelength-related component of the signal observed in the lightsensor. In an example embodiment, at least one light source used in aidof gesture recognition may be modulated in time using a code having afrequency component greater than 100 Hz, 1000 Hz, 10 kHz, or 100 kHz. Inan example embodiment, the light sensor may have a temporal responsehaving a cutoff frequency greater than said frequency components. Inembodiments, circuitry may be employed to ensure that the frequencycomponent corresponding to gesture recognition can be extracted andmonitored, with the background components related to the room ambient,the display illumination, and other such non-gesture-related backgroundinformation substantially removed. In this example, the light sensors,even though they absorb both visible and infrared light, can provide asignal that is primarily related to gestural information of interest ingesture recognition.

In an example embodiment, an optical source having a total optical powerof approximately 1 mW may be employed. When illuminating an object adistance approximately 10 cm away, where the object has areaapproximately 1 cm² and diffuse reflectance approximately 20%, then theamount of power incident on a light sensor having area 1 cm2 may be oforder 100 pW. In an example embodiment, a light sensor having absorbanceof 1% may be employed, corresponding to a photocurrent related to thelight received as a consequence of the illumination via the opticalsource, and reflected or scattered off of the object, and thus incidentonto the light sensor, may therefore be of order pW. In exampleembodiments, the electrical signal reported by the light sensor maycorrespond to approximately pA signal component at the modulationfrequency of the optical source. In example embodiments, a largeadditional signal component, such as in the nA or to range, may arisedue to visible and infrared background, display light, etc. In exampleembodiments, the relatively small signal components, with itsdistinctive temporal and/or spatial signature as provided by modulation(in time and/or space) of the illumination source, may nevertheless beisolated relative to other background/signal, and may be employed todiscern gestural information.

In embodiments, light-absorbing material 405 may consist of a materialthat principally absorbs infrared light in a certain band; and that issubstantially transparent to visible-wavelength light. In an exampleembodiment, a material such as PBDTT-DPP, the near-infraredlight-sensitive polymerpoly(2,60-4,8-bis(5-ethylhexylthienyl)benzo-[1,2-b;3,4-b]dithiophene-alt-5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione),may be employed as a component of the light-absorbing layer.

In embodiments, the electronic signal produced by the light sensor maybe communicated to a device for electronic amplification. This devicemay amplify a specific electronic frequency band more than other bands,producing an enhanced signal component that is related to the gesturalinformation. The signal from the light sensor, possibly with thecombination of amplification (potentially frequency-dependent), may beinput to an analog-to-digital converter that can produce a digitalsignal related to the gestural information. The digital informationrelated to gestural information can be further conveyed to otherintegrated circuits and/or signal processing engines in the context of asystem. For example, it may be conveyed to an application processor.

In embodiments, optical sources used to illuminate a volume of space,with the goal of enabling gesture recognition, may use illumination at anear infrared wavelength that is substantially unseen by the human eye.In an example embodiment, a light-emitting diode having centerwavelength of approximately 950 nm may be employed.

In embodiments, gesture recognition may be accomplished by combininginformation from at least one camera, embedded into the computingdevice, and having a lens providing a substantially focused image ontoan image sensor that is part of the camera; and may also incorporatesensors in the peripheral region, and/or integrated into the displayregion. In embodiments, the distributed sensors may provide generalinformation on the spatio-temporal movements of the object being imaged;and the signals from the at least one camera(s) may be combined with thedistributed sensors' signals to provide a morespatially-/temporally-accurate picture of the two- or three-dimensionalmotion of the object whose gesture is to be recognized. In an exampleembodiment, the camera may employ an image sensor providing a modestspatial resolution, such as QVGA, VGA, SVGA, etc., and thus beimplemented using an image sensor having small die size and thus lowcost; and also be implemented using a camera module having small x, y,and z form factor, enabling minimal consumption of peripheral regionarea, and no substantial addition to the z-height of the tablet or othercomputing device. In embodiments, a moderate frame rate, such as 15 fps,30 fps, or 60 fps may be employed, which, combined with a modestresolution, enables a low-cost digital communication channel andmoderate complexity of signal processing in the recognition of gestures.In embodiments, the at least one camera module may implement wide fieldof view imaging in order to provide a wide angular range in theassessment of gestures in relation to a display. In embodiments, atleast one camera module may be tilted, having its angle of regardnonparallel to the normal direction (perpendicular direction) to thedisplay, enabling the at least one camera to image an angular extent incloser proximity to the display. In embodiments, multiple cameras may beemployed in combination, each having an angle of regard distinct from atleast one another, thereby enabling gestures in moderate proximity tothe display to be imaged and interpreted. In embodiments, the at leastone camera may employ an image sensor sensitized using light-detectingmaterials that provide high quantum efficiency, for example, greaterthan 30%, at near infrared wavelength used by the illuminating source;this enables reduced requirement for power and/or intensity in theilluminating source. In embodiments, the illuminating source may bemodulated in time at a specific frequency and employing a specifictemporal pattern (e.g., a series of pulses of known spacing and width intime); and the signal from the at least one camera and/or the at leastone distributed sensor may be interpreted with knowledge of the phaseand temporal profile of the illuminating source; and in this manner,increased signal-to-noise ratio, akin to lock-in or boxcar-averaging orother filtering and/or analog or digital signal processing methods, maybe used to substantially pinpoint the moduled, hence illuminated signal,and substantially remove or minimize the background signal associatedwith the background scene.

FIG. 31 shows an embodiment of a method of gesture recognition. Themethod comprises an operation 501 that includes acquiring a stream intime of at least two images from each of at least one of the cameramodule(s); and an operation 507 that includes also acquiring a stream,in time, of at least two signals from each of at least one of the lightsensors. The method further comprises, at operations 503 and 509,conveying the images and/or signals to a processor. The method furthercomprises, at operation 505, using the processor, an estimate of agesture's meaning, and timing, based on the combination of the imagesand signals.

FIG. 32 shows an embodiment of a method of gesture recognition. Themethod comprises an operation 601 that includes acquiring a stream intime of at least two images from each of at least one of the cameramodules; and an operation 607 that includes also acquiring a stream, intime, of at least two signals from each of at least one of thetouch-based interface devices. The method further comprises, atoperations 603 and 609, conveying the images and/or signals to aprocessor. The method further comprises, at operation 605, using theprocessor, an estimate of a gesture's meaning, and timing, based on thecombination of the images and signals.

In embodiments, signals received by at least one of (1) the touch-basedinterface devices; (2) the camera modules; (3) the light sensors, eachof these either within the peripheral and/or the display ordisplay/input regions, may be employed and, singly or jointly, used todetermine the presence, and the type, of gesture indicated by a user ofthe device.

Referring again to FIG. 16, in embodiments, a stream, in time, of imagesis acquired from each of at least one of the camera modules. A stream,in time, of at least two signals from each of at least one of the lightsensors is also acquired. In embodiments, the streams may be acquiredfrom the different classes of peripheral devices synchronously. Inembodiments, the streams may be acquired with known time stampsindicating when each was acquired relative to the others, for example,to some conference reference time point. In embodiments, the streams areconveyed to a processor. The processor computes an estimate of thegesture's meaning, and timing, based on the combination of the imagesand signals.

In embodiments, at least one camera module has a wide field of viewexceeding about 40°. In embodiments, at least one camera module employsa fisheye lens. In embodiments, at least one image sensor achieveshigher resolution at its center, and lower resolution in its periphery.In embodiments, at least one image sensor uses smaller pixels near itscenter and larger pixels near its periphery.

In embodiments, active illumination via at least one light source;combined with partial reflection and/or partial scattering off of aproximate object; combined with light sensing using at least one opticalmodule or light sensor; may be combined to detect proximity to anobject. In embodiments, information regarding such proximity may be usedto reduce power consumption of the device. In embodiments, powerconsumption may be reduced by dimming, or turning off, power-consumingcomponents such as a display.

In embodiments, at least one optical source may emit infrared light. Inembodiments, at least one optical source may emit infrared light in thenear infrared between about 700 nm and about 1100 nm. In embodiments, atleast one optical source may emit infrared light in the short-wavelengthinfrared between about 1100 nm and about 1700 nm wavelength. Inembodiments, the light emitted by the optical source is substantiallynot visible to the user of the device.

In embodiments, at least one optical source may project a structuredlight image. In embodiments, spatial patterned illumination, combinedwith imaging, may be employed to estimate the relative distance ofobjects relative to the imaging system.

In embodiments, at least two lensing systems may be employed to image ascene, or portions of a scene, onto two distinct regions of amonolithically-integrated single image sensor integrated circuit; andthe patterns of light thus acquired using the image sensor integratedcircuit may be used to aid in estimating the relative or absolutedistances of objects relative to the image sensor system.

In embodiments, at least two lensing systems may be employed to image ascene, or portions of a scene, onto two distinct image sensor integratedcircuits housed within a single camera system; and the patterns of lightthus acquired using the image sensor integrated circuits may be used toaid in estimating the relative or absolute distances of objects relativeto the image sensor system.

In embodiments, at least two lensing systems may be employed to image ascene, or portions of a scene, onto two distinct image sensor integratedcircuits housed within separate camera systems or subsystems; and thepatterns of light thus acquired using the image sensor integratedcircuits may be used to aid in estimating the relative or absolutedistances of objects relative to the image sensor systems or subsystems.

In embodiments, the different angles of regard, or perspectives, fromwhich the at least two optical systems perceive the scene, may be usedto aid in estimating the relative or absolute distances of objectsrelative to the image sensor system.

In embodiments, light sensors such as the light sensors 115A, 115Bsituated in the peripheral region 101 of FIG. 27, and/or the lightsensors 107A, 107B situated in the display region 103 of FIG. 27, may beused singly, or in combination with one another, and/or in combinationwith camera modules, to acquire information about a scene. Inembodiments, light sensors may employ lenses to aid in directing lightfrom certain regions of a scene onto specific light sensors. Inembodiments, light sensors may employ systems for aperturing, such aslight-blocking housings, that define a limited angular range over whichlight from a scene will impinge on a certain light sensor. Inembodiments, a specific light sensor will, with the aid of aperturing,be responsible for sensing light from within a specific angular cone ofincidence.

In embodiments, the different angles of regard, or perspectives, fromwhich the at least two optical systems perceive the scene, may be usedto aid in estimating the relative or absolute distances of objectsrelative to the image sensor system.

In embodiments, the time sequence of light detector from at least twolight sensors may be used to estimate the direction and velocity of anobject. In embodiments, the time sequence of light detector from atleast two light sensors may be used to ascertain that a gesture was madeby a user of a computing device. In embodiments, the time sequence oflight detector from at least two light sensors may be used to classifythe gesture that was made by a user of a computing device. Inembodiments, information regarding the classification of a gesture, aswell as the estimated occurrence in time of the classified gesture, maybe conveyed to other systems or subsystems within a computing device,including to a processing unit.

In embodiments, light sensors may be integrated into the display regionof a computing device, for example, the light sensors 107A, 107B of FIG.27. In embodiments, the incorporation of the light sensors into thedisplay region can be achieved without the operation of the display inthe conveyance of visual information to the user being substantiallyaltered. In embodiments, the display may convey visual information tothe user principally using visible wavelengths in the range of about 400nm to about 650 nm, while the light sensors may acquire visualinformation regarding the scene principally using infrared light ofwavelengths longer than about 650 nm. In embodiments, a ‘display plane’operating principally in the visible wavelength region may reside infront of—closer to the user—than a ‘light sensing plane’ that mayoperate principally in the infrared spectral region.

In embodiments, structured light of a first type may be employed, and ofa second type may also be employed, and the information from the atleast two structured light illuminations may be usefully combined toascertain information regarding a scene that exceeds the informationcontained in either isolated structured light image.

In embodiments, structured light of a first type may be employed toilluminate a scene and may be presented from a first source providing afirst angle of illumination; and structured light of a second type maybe employed to illuminate a scene and may be presented from a secondsource providing a second angle of illumination.

In embodiments, structured light of a first type and a first angle ofillumination may be sensed using a first image sensor providing a firstangle of sensing; and also using a second image sensor providing asecond angle of sensing.

In embodiments, structured light having a first pattern may be presentedfrom a first source; and structured light having a second pattern may bepresented from a second source.

In embodiments, structured light having a first pattern may be presentedfrom a source during a first time period; and structured light having asecond pattern may be presented from a source during a second timeperiod.

In embodiments, structured light of a first wavelength may be used toilluminate a scene from a first source having a first angle ofillumination; and structured light of a second wavelength may be used toilluminate a scene from a second source having a second angle ofillumination.

In embodiments, structured light of a first wavelength may be used toilluminate a scene using a first pattern; and structured light of asecond wavelength may be used to illuminate a scene using a secondpattern. In embodiments, a first image sensor may sense the scene with astrong response at the first wavelength and a weak response at thesecond wavelength; and a second image sensor may sense the scene with astrong response at the second wavelength and a weak response at thefirst wavelength. In embodiments, an image sensor may consist of a firstclass of pixels having strong response at the first wavelength and weakresponse at the second wavelength; and of a second class of pixelshaving strong response at the second wavelength and weak response at thefirst wavelength.

Embodiments include image sensor systems that employ a filter having afirst bandpass spectral region; a first bandblock spectral region; and asecond bandpass spectral region. Embodiments include the first bandpassregion corresponding to the visible spectral region; the first bandblockspectral region corresponding to a first portion of the infrared; andthe second bandpass spectral region corresponding to a second portion ofthe infrared. Embodiments include using a first time period to detectprimarily the visible-wavelength scene; and using active illuminationwithin the second bandpass region during a second time period to detectthe sum of a visible-wavelength scene and an actively-illuminatedinfrared scene; and using the difference between images acquired duringthe two time periods to infer a primarily actively-illuminated infraredscene. Embodiments include using structured light during the second timeperiod. Embodiments include using infrared structured light. Embodimentsinclude using the structured light images to infer depth informationregarding the scene; and in tagging, or manipulating, the visible imagesusing information regarding depth acquired based on the structured lightimages.

In embodiments, gestures inferred may include one-thumb-up;two-thumbs-up; a finger swipe; a two-finger swipe; a three-finger swipe;a four-finger-swipe; a thumb plus one finger swipe; a thumb plus twofinger swipe; etc. In embodiments, gestures inferred may includemovement of a first digit in a first direction; and of a second digit ina substantially opposite direction. Gestures inferred may include atickle.

Sensing of the intensity of light incident on an object may be employedin a number of applications. One such application includes estimation ofambient light levels incident upon an object so that the object's ownlight-emission intensity can be suitable selected. In mobile devicessuch as cell phones, personal digital assistants, smart phones, and thelike, the battery life, and thus the reduction of the consumption ofpower, are of importance. At the same time, the visual display ofinformation, such as through the use of a display such as those based onLCDs or pixellated LEDs, may also be needed. The intensity with whichthis visual information is displayed depends at least partially on theambient illumination of the scene. For example, in very bright ambientlighting, more light intensity generally needs to be emitted by thedisplay in order for the display's visual impression or image to beclearly visible above the background light level. When ambient lightingis weaker, it is feasible to consume less battery power by emitting alower level of light from the display.

As a result, it is of interest to sense the light level near or in thedisplay region. Existing methods of light sensing often include asingle, or a very few, light sensors, often of small area. This can leadto undesired anomalies and errors in the estimation of ambientillumination levels, especially when the ambient illumination of thedevice of interest is spatially inhomogeneous. For example, shadows dueto obscuring or partially obscuring objects may—if they obscure one or afew sensing elements—result in a display intensity that is less brightthan desirable under the true average lighting conditions.

Embodiments include realization of a sensor, or sensors, that accuratelypermit the determination of light levels. Embodiments include at leastone sensor realized using solution-processed light-absorbing materials.Embodiments include sensors in which colloidal quantum dot filmsconstitute the primary light-absorbing element. Embodiments includesystems for the conveyance of signals relating to the light levelimpinging on the sensor that reduce, or mitigate, the presence of noisein the signal as it travels over a distance between a passive sensor andactive electronics that employ the modulation of electrical signals usedin transduction. Embodiments include systems that include (1) thelight-absorbing sensing element; (2) electrical interconnect for theconveyance of signals relating to the light intensity impinging upon thesensing element; and (3) circuitry that is remote from thelight-absorbing sensing element, and is connected to it via theelectrical interconnect, that achieves low-noise conveyance of thesensed signal through the electrical interconnect. Embodiments includesystems in which the length of interconnect is more than one centimeterin length. Embodiments include systems in which interconnect does notrequire special shielding yet achieve practically useful signal-to-noiselevels.

Embodiments include sensors, or sensor systems, that are employed,singly or in combination, to estimate the average color temperatureilluminating the display region of a computing device. Embodimentsinclude sensors, or sensor systems, that accept light from a wideangular range, such as greater than about ±20° to normal incidence, orgreater than about ±30° to normal incidence, or greater than about ±40°to normal incidence. Embodiments include sensors, or sensor systems,that include at least two types of optical filters, a first type passingprimarily a first spectral band, a second type passing primarily asecond spectral band. Embodiments include using information from atleast two sensors employing at least two types of optical filters toestimate color temperature illuminating the display region, or a regionproximate the display region.

Embodiments include systems employing at least two types of sensors.Embodiments include a first type constituted of a first light-sensingmaterial, and a second type constituted of a second light-sensingmaterial. Embodiments include a first light-sensing material configuredto absorb, and transduce, light in a first spectral band, and a secondlight-sensing material configured to transduce a second spectral band.Embodiments include a first light-sensing material employing a pluralityof nanoparticles having a first average diameter, and a secondlight-sensing material employing a plurality of nanoparticles have asecond average diameter. Embodiments include a first diameter in therange of approximately 1 nm to approximately 2 nm, and a second diametergreater than about 2 nm.

Embodiments include methods of incorporating a light-sensing materialinto, or onto, a computing device involving ink-jet printing.Embodiments include using a nozzle to apply light-sensing material overa defined region. Embodiments include defining a primary light-sensingregion using electrodes. Embodiments include methods of fabricatinglight sensing devices integrated into, or onto, a computing deviceinvolving: defining a first electrode; defining a second electrode;defining a light-sensing region in electrical communication with thefirst and the second electrode. Embodiments include methods offabricating light sensing devices integrated into, or onto, a computingdevice involving: defining a first electrode; defining a light-sensingregion; and defining a second electrode; where the light sensing regionis in electrical communication with the first and the second electrode.

Embodiments include integration at least two types of sensors into, oronto, a computing device, using ink-jet printing. Embodiments includeusing a first reservoir containing a first light-sensing materialconfigured to absorb, and transduce, light in a first spectral band; andusing a second reservoir containing a second light-sensing materialconfigured to absorb, and transduce, light in a second spectral band.

Embodiments include the use of differential or modulated signaling inorder to substantially suppress any external interference. Embodimentsinclude subtracting dark background noise.

Embodiments include a differential system depicted in FIG. 33. FIG. 33shows an embodiment of a three-electrode differential-layout system 700to reduce external interferences with light sensing operations. Thethree-electrode differential-layout system 700 is shown to include alight sensing material covering all three electrodes 701, 703, 705. Alight-obscuring material 707 (Black) prevents light from impinging uponthe light-sensing material in a region that is electrically accessedusing the first electrode 701 and the second electrode 703. Asubstantially transparent material 709 (Clear) allows light to impingeupon the light-sensing material in a substantially distinct region thatis electrically accessed using the second electrode 703 and the thirdelectrode 705. The difference in the current flowing through theClear-covered electrode pair and the Black-covered electrode pair isequal to the photocurrent—that is, this difference does not include anydark current, but instead is proportional to the light intensity, withany dark offset substantially removed.

Embodiments include the use of a three-electrode system as follows. Eachelectrode consists of a metal wire. Light-absorbing material may be inelectrical communication with the metal wires. Embodiments include theencapsulation of the light-absorbing material using a substantiallytransparent material that protects the light-absorbing material fromambient environmental conditions such as air, water, humidity, dust, anddirt. The middle of the three electrodes may be biased to a voltage V₁,where an example of a typical voltage is about 0 V. The two outerelectrodes may be biased to a voltage V₂, where a typical value is about3 V. Embodiments include covering a portion of the device usinglight-obscuring material that substantially prevents, or reduces, theincidence of light on the light-sensing material.

The light-obscuring material ensures that one pair of electrodes seeslittle or no light. This pair is termed the dark, or reference,electrode pair. The use of a transparent material over the otherelectrode pair ensures that, if light is incident, it is substantiallyincident upon the light-sensing material. This pair is termed the lightelectrode pair.

The difference in the current flowing through the light electrode pairand the dark electrode pair is equal to the photocurrent—that is, thisdifference does not include any dark current, but instead isproportional to the light intensity, with any dark offset substantiallyremoved.

In embodiments, these electrodes are wired in twisted-pair form. In thismanner, common-mode noise from external sources is reduced or mitigated.Referring to FIG. 34, electrodes 801, 803, 805 with twisted pair layout800, the use of a planar analogue of a twisted-pair configuration leadsto reduction or mitigation of common-mode noise from external sources.

In another embodiment, biasing may be used such that the light-obscuringlayer may not be required. The three electrodes may be biased to threevoltages V₁, V₂, and V₃. In one example, V₁=6 V, V₂=3 V, V₃=0 V. Thelight sensor between 6 V and 3 V, and that between 0 V and 3 V, willgenerate opposite-direction currents when read between the 6 V and 0 Vlevels. The resultant differential signal is then transferred out intwisted-pair fashion.

In embodiments, the electrode layout may itself be twisted, furtherimproving the noise-resistance inside the sensor. In this case, anarchitecture is used in which an electrode may cross over another.

In embodiments, electrical bias modulation may be employed. Analternating bias may be used between a pair of electrodes. Thephotocurrent that flows will substantially mimic the temporal evolutionof the time-varying electrical biasing. Readout strategies includefiltering to generate a low-noise electrical signal. The temporalvariations in the biasing include sinusoidal, square, or other periodicprofiles. For example, referring to FIG. 35, an embodiment oftime-modulated biasing 900 a signal 901 applied to electrodes to reduceexternal noise that is not at the modulation frequency. Modulating thesignal in time allows rejection of external noise that is not at themodulation frequency.

Embodiments include combining the differential layout strategy with themodulation strategy to achieve further improvements in signal-to-noiselevels.

Embodiments include employing a number of sensors having differentshapes, sizes, and spectral response (e.g., sensitivities to differentcolors). Embodiments include generating multi-level output signals.Embodiments include processing signals using suitable circuits andalgorithms to reconstruct information about the spectral and/or otherproperties of the light incident.

Advantages of the disclosed subject matter include transfer of accurateinformation about light intensity over longer distances than wouldotherwise be possible. Advantages include detection of lower levels oflight as a result. Advantages include sensing a wider range of possiblelight levels. Advantages include successful light intensitydetermination over a wider range of temperatures, an advantageespecially conferred when the dark reference is subtracted using thedifferential methods described herein.

Embodiments include a light sensor including a first electrode, a secondelectrode, and a third electrode. A light-absorbing semiconductor is inelectrical communication with each of the first, second, and thirdelectrodes. A light-obscuring material substantially attenuates theincidence of light onto the portion of light-absorbing semiconductorresiding between the second and the third electrodes, where anelectrical bias is applied between the second electrode and the firstand third electrodes and where the current flowing through the secondelectrode is related to the light incident on the sensor.

Embodiments include a light sensor including a first electrode, a secondelectrode, and a light-absorbing semiconductor in electricalcommunication with the electrodes wherein a time-varying electrical biasis applied between the first and second electrodes and wherein thecurrent flowing between the electrodes is filtered according to thetime-varying electrical bias profile, wherein the resultant component ofcurrent is related to the light incident on the sensor.

Embodiments include the above embodiments where the first, second, andthird electrodes consists of a material chosen from the list: gold,platinum, palladium, silver, magnesium, manganese, tungsten, titanium,titanium nitride, titanium dioxide, titanium oxynitride, aluminum,calcium, and lead.

Embodiments include the above embodiments where the light-absorbingsemiconductor includes materials taken from the list: PbS, PbSe, PbTe,SnS, SnSe, SnTe, CdS, CdSe, CdTe, Bi₂S₃, In₂S₃, In₂S₃, In₂Te₃, ZnS,ZnSe, ZnTe, Si, Ge, GaAs, polypyrolle, pentacene, polyphenylenevinylene,polyhexylthiophene, and phenyl-C61-butyric acid methyl ester.

Embodiments include the above embodiments where the bias voltages aregreater than about 0.1 V and less than about 10 V. Embodiments includethe above embodiments where the electrodes are spaced a distance betweenabout 1 μm and about 20 μm from one another.

Embodiments include the above embodiments where the distance between thelight-sensing region and active circuitry used in biasing and reading isgreater than about 1 cm and less than about 30 cm.

The capture of visual information regarding a scene, such as viaimaging, is desired in a range of areas of application. In cases, theoptical properties of the medium residing between the imaging system,and the scene of interest, may exhibit optical absorption, opticalscattering, or both. In cases, the optical absorption and/or opticalscattering may occur more strongly in a first spectral range compared toa second spectral range. In cases, the strongly-absorbing-or-scatteringfirst spectral range may include some or all of the visible spectralrange of approximately 470 nm to approximately 630 nm, and themore-weakly-absorbing-or-scattering second spectral range may includeportions of the infrared spanning a range of approximately 650 nm toapproximately 24 μm wavelengths.

In embodiments, image quality may be augmented by providing an imagesensor array having sensitivity to wavelengths longer than about a 650nm wavelength.

In embodiments, an imaging system may operate in two modes: a first modefor visible-wavelength imaging; and a second mode for infrared imaging.In embodiments, the first mode may employ a filter that substantiallyblocks the incidence of light of some infrared wavelengths onto theimage sensor.

Referring now to FIG. 36, an embodiment of a transmittance spectrum 1000of a filter that may be used in various imaging applications.Wavelengths in the visible spectral region 1001 are substantiallytransmitted, enabling visible-wavelength imaging. Wavelengths in theinfrared bands 1003 of approximately 750 nm to approximately 1450 nm,and also in a region 1007 beyond about 1600 nm, are substantiallyblocked, reducing the effect of images associated with ambient infraredlighting. Wavelengths in the infrared band 1005 of approximately 1450 nmto approximately 1600 nm are substantially transmitted, enablinginfrared-wavelength imaging when an active source having its principalspectral power within this band is turned on.

In embodiments, an imaging system may operate in two modes: a first modefor visible-wavelength imaging; and a second mode for infrared imaging.In embodiments, the system may employ an optical filter, which remainsin place in each of the two modes, that substantially blocks incidenceof light over a first infrared spectral band; and that substantiallypasses incidence of light over a second infrared spectral band. Inembodiments, the first infrared spectral band that is blocked may spanfrom about 700 nm to about 1450 nm. In embodiments, the second infraredspectral band that is substantially not blocked may begin at about 1450nm. In embodiments, the second infrared spectral band that issubstantially not blocked may end at about 1600 nm. In embodiments, inthe second mode for infrared imaging, active illuminating that includespower in the second infrared spectral band that is substantially notblocked may be employed. In embodiments, a substantiallyvisible-wavelength image may be acquired via image capture in the firstmode. In embodiments, a substantially actively-infrared-illuminatedimage may be acquired via image capture in the second mode. Inembodiments, a substantially actively-infrared-illuminated image may beacquired via image capture in the second mode aided by the subtractionof an image acquired during the first mode. In embodiments, aperiodic-in-time alternation between the first mode and second mode maybe employed. In embodiments, a periodic-in-time alternation betweenno-infrared-illumination, and active-infrared-illumination, may beemployed. In embodiments, a periodic-in-time alternation betweenreporting a substantially visible-wavelength image, and reporting asubstantially actively-illuminated-infrared image, may be employed. Inembodiments, a composite image may be generated which displays, inoverlaid fashion, information relating to the visible-wavelength imageand the infrared-wavelength image. In embodiments, a composite image maybe generated which uses a first visible-wavelength color, such as blue,to represent the visible-wavelength image; and uses a secondvisible-wavelength color, such as red, to represent theactively-illuminated infrared-wavelength image, in a manner that isoverlaid.

In image sensors, a nonzero, nonuniform, image may be present even inthe absence of illumination, (in the dark). If not accounted for, thedark images can lead to distortion and noise in the presentation ofilluminated images.

In embodiments, an image may be acquired that represents the signalpresent in the dark. In embodiments, an image may be presented at theoutput of an imaging system that represents the difference between anilluminated image and the dark image. In embodiments, the dark image maybe acquired by using electrical biasing to reduce the sensitivity of theimage sensor to light. In embodiments, an image sensor system may employa first time interval, with a first biasing scheme, to acquire asubstantially dark image; and a second time interval, with a secondbiasing scheme, to acquire a light image. In embodiments, the imagesensor system may store the substantially dark image in memory; and mayuse the stored substantially dark image in presenting an image thatrepresents the difference between a light image and a substantially darkimage. Embodiments include reducing distortion, and reducing noise,using the method.

In embodiments, a first image may be acquired that represents the signalpresent following reset; and a second image may be acquired thatrepresents the signal present following an integration time; and animage may be presented that represents the difference between the twoimages. In embodiments, memory may be employed to store at least one oftwo of the input images. In embodiments, the result difference image mayprovide temporal noise characteristics that are consistent withcorrelated double-sampling noise. In embodiments, an image may bepresented having equivalent temporal noise considerable less than thatimposed by sqrt(kTC) noise.

Embodiments include high-speed readout of a dark image; and of a lightimage; and high-speed access to memory and high-speed image processing;to present a dark-subtracted image to a user rapidly.

Embodiments include a camera system in which the interval between theuser indicating that an image is to be acquired; and in which theintegration period associated with the acquisition of the image; is lessthan about one second. Embodiments include a camera system that includesa memory element in between the image sensor and the processor.

Embodiments include a camera system in which the time in between shotsis less than about one second.

Embodiments include a camera system in which a first image is acquiredand stored in memory; and a second image is acquired; and a processor isused to generate an image that employs information from the first imageand the second image. Embodiments include generating an image with highdynamic range by combining information from the first image and thesecond image. Embodiments include a first image having a first focus;and a second image having a second focus; and generating an image fromthe first image and the second image having higher equivalent depth offocus.

Hotter objects generally emit higher spectral power density at shorterwavelengths than do colder objects. Information may thus be extractedregarding the relative temperatures of objects imaged in a scene basedon the ratios of power in a first band to the power in a second band.

In embodiments, an image sensor may comprise a first set of pixelsconfigured to sense light primarily within a first spectral band; and asecond set of pixels configured to sense light primarily within a secondspectral band. In embodiments, an inferred image may be reported thatcombines information from proximate pixels of the first and second sets.In embodiments, an inferred image may be reported that provides theratio of signals from proximate pixels of the first and second sets.

In embodiments, an image sensor may include a means of estimating objecttemperature; and may further include a means of acquiringvisible-wavelength images. In embodiments, image processing may be usedto false-color an image representing estimated relative objecttemperature atop a visible-wavelength image.

In embodiments, the image sensor may include at least one pixel havinglinear dimensions less than approximately 2 μm×2 μm.

In embodiments, the image sensor may include a first layer providingsensing in a first spectral band; and a second layer providing sensingin a second spectral band.

In embodiments, visible images can be used to present a familiarrepresentation to users of a scene; and infrared images can provideadded information, such as regarding temperature, or pigment, or enablepenetration through scattering and/or visible-absorbing media such asfog, haze, smoke, or fabrics.

In cases, it may be desired to acquire both visible and infrared imagesusing a single image sensor. In cases, registration among visible andinfrared images is thus rendered substantially straightforward.

In embodiments, an image sensor may employ a single class oflight-absorbing light-sensing material; and may employ a patterned layerabove it that is responsible for spectrally-selective transmission oflight through it, also known as a filter. In embodiments, thelight-absorbing light-sensing material may providehigh-quantum-efficiency light sensing over both the visible and at leasta portion of the infrared spectral regions. In embodiments, thepatterned layer may enable both visible-wavelength pixel regions, andalso infrared-wavelength pixel regions, on a single image sensorcircuit.

In embodiments, an image sensor may employ two classes oflight-absorbing light-sensing materials: a first material configured toabsorb and sense a first range of wavelengths; and a second materialconfigured to absorb and sense a second range of wavelengths. The firstand second ranges may be at least partially overlapping, or they may notbe overlapping.

In embodiments, two classes of light-absorbing light-sensing materialsmay be placed in different regions of the image sensor. In embodiments,lithography and etching may be employed to define which regions arecovered using which light-absorbing light-sensing materials. Inembodiments, ink-jet printing may be employed to define which regionsare covered using which light-absorbing light-sensing materials.

In embodiments, two classes of light-absorbing light-sensing materialsmay be stacked vertically atop one another. In embodiments, a bottomlayer may sense both infrared and visible light; and a top layer maysense visible light principally.

In embodiments, an optically-sensitive device may include: a firstelectrode; a first light-absorbing light-sensing material; a secondlight-absorbing light-sensing material; and a second electrode. Inembodiments, a first electrical bias may be provided between the firstand second electrodes such that photocarriers are efficiently collectedprimarily from the first light-absorbing light-sensing material. Inembodiments, a second electrical bias may be provided between the firstand second electrodes such that photocarriers are efficiently collectedprimarily from the second light-absorbing light-sensing material. Inembodiments, the first electrical bias may result in sensitivityprimarily to a first wavelength of light. In embodiments, the secondelectrical bias may result in sensitivity primarily to a secondwavelength of light. In embodiments, the first wavelength of light maybe infrared; and the second wavelength of light may be visible. Inembodiments, a first set of pixels may be provided with the first bias;and a second set of pixels may be provided with the second bias;ensuring that the first set of pixels responds primarily to a firstwavelength of light, and the second set of pixels responds primarily toa second wavelength of light.

In embodiments, a first electrical bias may be provided during a firstperiod of time; and a second electrical bias may be provided during asecond period of time; such that the image acquired during the firstperiod of time provides information primarily regarding a firstwavelength of light; and the image acquired during the second period oftime provides information primarily regarding a second wavelength oflight. In embodiments, information acquired during the two periods oftime may be combined into a single image. In embodiments, false-colormay be used to represent, in a single reported image, informationacquired during each of the two periods of time.

In embodiments, a focal plane array may consist of a substantiallylaterally-spatially uniform film having a substantiallylaterally-uniform spectral response at a given bias; and having aspectral response that depends on the bias. In embodiments, a spatiallynonuniform bias may be applied, for example, different pixel regions maybias the film differently. In embodiments, under a givenspatially-dependent biasing configuration, different pixels may providedifferent spectral responses. In embodiments, a first class of pixelsmay be responsive principally to visible wavelengths of light, while asecond class of pixels may be responsive principally to infraredwavelengths of light. In embodiments, a first class of pixels may beresponsive principally to one visible-wavelength color, such as blue;and a second class of pixels may be responsive principally to adistinctive visible-wavelength color, such as green; and a third classof pixels may be responsive principally to a distinctivevisible-wavelength color, such as red.

In embodiments, an image sensor may comprise a readout integratedcircuit, at least one pixel electrode of a first class, at least onepixel electrode of a second class, a first layer of optically sensitivematerial, and a second layer of optically sensitive material. Inembodiments, the image sensor may employ application of a first bias forthe first pixel electrode class; and of a second bias to the secondpixel electrode class.

In embodiments, those pixel regions corresponding to the first pixelelectrode class may exhibit a first spectral response; and of the secondpixel electrode class may exhibit a second spectral response; where thefirst and second spectral responses are significantly different. Inembodiments, the first spectral response may be substantially limited tothe visible-wavelength region. In embodiments, the second spectralresponse may be substantially limited to the visible-wavelength region.In embodiments, the second spectral response may include both portionsof the visible and portions of the infrared spectral regions.

In embodiments, it may be desired to fabricate an image sensor havinghigh quantum efficiency combined with low dark current.

In embodiments, a device may consist of: a first electrode; a firstselective spacer; a light-absorbing material; a second selective spacer;and a second electrode.

In embodiments, the first electrode may be used to extract electrons. Inembodiments, the first selective spacer may be used to facilitate theextraction of electrons but block the injection of holes. Inembodiments, the first selective spacer may be an electron-transportlayer. In embodiments, the light-absorbing material may includesemiconductor nanoparticles. In embodiments, the second selective spacermay be used to facilitate the extraction of holes but block theinjection of electrons. In embodiments, the second selective spacer maybe a hole-transport layer.

In embodiments, only a first selective spacer may be employed. Inembodiments, the first selective spacer may be chosen from the list:TiO2, ZnO, ZnS. In embodiments, the second selective spacer may be NiO.In embodiments, the first and second electrode may be made using thesame material. In embodiments, the first electrode may be chosen fromthe list: TiN, W, Al, Cu. In embodiments, the second electrode may bechosen from the list: ZnO, Al:ZnO, ITO, MoO3, Pedot, Pedot:PSS.

In embodiments, it may be desired to implement an image sensor in whichthe light-sensing element can be configured during a first interval toaccumulate photocarriers; and during a second interval to transferphotocarriers to another node in a circuit.

Embodiments include a device comprising: a first electrode; a lightsensing material; a blocking layer; and a second electrode.

Embodiments include electrically biasing the device during a firstinterval, known as the integration period, such that photocarriers aretransported towards the first blocking layer; and where photocarriersare stored near the interface with the blocking layer during theintegration period.

Embodiments include electrically biasing the device during a secondinterval, known as the transfer period, such that the storedphotocarriers are extracted during the transfer period into another nodein a circuit.

Embodiments include a first electrode chosen from the list: TiN, W, Al,Cu. In embodiments, the second electrode may be chosen from the list:ZnO, Al:ZnO, ITO, MoO₃, Pedot, Pedot:PSS. In embodiments, the blockinglayer be chosen from the list: HfO₂, Al₂O₃, NiO, TiO₂, ZnO.

In embodiments, the bias polarity during the integration period may beopposite to that during the transfer period. In embodiments, the biasduring the integration period may be of the same polarity as that duringthe transfer period. In embodiments, the amplitude of the bias duringthe transfer period may be greater than that during the integrationperiod.

Embodiments include a light sensor in which an optically sensitivematerial functions as the gate of a silicon transistor. Embodimentsinclude devices comprising: a gate electrode coupled to a transistor; anoptically sensitive material; a second electrode. Embodiments includethe accumulation of photoelectrons at the interface between the gateelectrode and the optically sensitive material. Embodiments include theaccumulation of photoelectrons causing the accumulation of holes withinthe channel of the transistor. Embodiments include a change in the flowof current in the transistor as a result of a change in photoelectronsas a result of illumination. Embodiments include a change in currentflow in the transistor greater than 1000 electrons/s for everyelectron/s of change in the photocurrent flow in the optically sensitivelayer. Embodiments include a saturation behavior in which the transistorcurrent versus photons impinged transfer curve has a sublineardependence on photon fluence, leading to compression and enhanceddynamic range. Embodiments include resetting the charge in the opticallysensitive layer by applying a bias to a node on the transistor thatresults in current flow through the gate during the reset period.

Embodiments include combinations of the above image sensors, camerasystems, fabrication methods, algorithms, and computing devices, inwhich at least one image sensor is capable of operating in globalelectronic shutter mode.

In embodiments, at least two image sensors, or image sensor regions, mayeach operate in global shutter mode, and may provide substantiallysynchronous acquisition of images of distinct wavelengths, or fromdifferent angles, or employing different structured light.

Embodiments include implementing correlated double-sampling in theanalog domain. Embodiments include so doing using circuitry containedwithin each pixel. FIG. 37 shows an example schematic diagram of acircuit 1100 that may be employed within each pixel to reduce noisepower. In embodiments, a first capacitor 1101 (C₁) and a secondcapacitor 1103 (C₂) are employed in combination as shown. Inembodiments, the noise power is reduced according to the ratio C₂/C₁.

FIG. 38 shows an example schematic diagram of a circuit 1200 of aphotoGate/pinned-diode storage that may be implemented in silicon. Inembodiments, the photoGate/pinned-diode storage in silicon isimplemented as shown. In embodiments, the storage pinned diode is fullydepleted during reset. In embodiments, C₁ (corresponding to the lightsensor's capacitance, such as quantum dot film in embodiments) sees aconstant bias.

In embodiments, light sensing may be enabled through the use of a lightsensing material that is integrated with, and read using, a readoutintegrated circuit. Example embodiments of same are included in U.S.Provisional Application No. 61/352,409, entitled, “Stable, SensitivePhotodetectors and Image Sensors Made Therefrom Including Circuits forEnhanced Image Performance,” and U.S. Provisional Application No.61/352,410, entitled, “Stable, Sensitive Photodetectors and ImageSensors Made Therefrom Including Processes and Materials for EnhancedImage Performance,” both filed Jun. 8, 2010, which are herebyincorporated by reference in their entirety.

In embodiments, a method of gesture recognition is provided where themethod includes acquiring a stream, in time, of at least two images fromeach of at least one camera module; acquiring a stream, in time, of atleast two signals from each of at least one light sensor; and conveyingthe at least two images and the at least two signals to a processor, theprocessor being configured to generate an estimate of a gesture'smeaning, and timing, based on a combination of the at least two imagesand the at least two signals.

In embodiments, the at least one light sensor includes a light-absorbingmaterial having an absorbance, across the visible wavelength region ofabout 450 nm to about 650 nm, of less than about 30%.

In embodiments, the light-absorbing material includes PBDTT-DPP, thenear-infrared light-sensitive polymerpoly(2,60-4,8-bis(5-ethylhexylthienyl)benzo-[1,2-b;3,4-b]dithiophene-alt-5-dibutyloctyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4-dione).

In embodiments, the at least one light sensor includes a light-sensingmaterial capable of sensing infrared light.

In embodiments, the method includes modulating a light source using atleast one code selected from spatial codes and temporal codes.

In embodiments, the light source has an emission wavelength in the rangeof about 900 nm to about 1000 nm.

In one embodiment, a camera system includes a central imaging arrayregion, at least one light-sensing region outside of the central imagingarray region, a first mode, referred to as imaging mode, and a secondmode, referred to as sensing mode. The electrical power consumed in thesecond mode is at least 10 times lower than the electrical powerconsumed in the first mode.

In embodiments, the at least one light sensor includes a light-sensingmaterial capable of sensing infrared light.

In embodiments, light impinging on the light-sensing material is to bemodulated.

In embodiments, a portion of light impinging on the light-sensingmaterial is to be generated using a light emitter device having anemission wavelength in the range of about 800 nm to about 1000 nm.

In embodiments, the central imaging array includes at least sixmegapixels.

In embodiments, the central imaging array comprises pixels less thanapproximately 2 μm in width and approximately 2 μm in height.

In one embodiment, an image sensor circuit includes a central imagingarray region having a first field of view; and at least onelight-sensing region outside of the central imaging array region havinga second field of view. The second field of view is less than half,measured in angle, the field of view of the first field of view.

In one embodiment, an integrated circuit includes a substrate, an imagesensing array region occupying a first region of said semiconductorsubstrate and including a plurality of optically sensitive pixelregions, a pixel circuit for each pixel region, each pixel circuitcomprising a charge store and a read-out circuit, and a light-sensitiveregion outside of the image sensing array region. The image sensingarray region having a first field of view and the light-sensitive regionhaving a second field of view; the angle of the second field of view isless than half of the angle of the first field of view.

In embodiments, at least one of the image sensing array and thelight-sensitive region outside of the image sensing array regionincludes a light-sensing material capable of sensing infrared light.

In embodiments, light impinging on at least one of the image sensingarray and the light-sensitive region outside of the image sensing arrayregion is to be modulated.

In embodiments, a portion of light impinging on at least one of theimage sensing array and the light-sensitive region outside of the imagesensing array region is to be generated using a light emitter devicehaving an emission wavelength in the range of about 800 nm to about 1000nm.

In embodiments, the image sensing array includes at least sixmegapixels.

In embodiments, the image sensing array comprises pixels less thanapproximately 2 μm in width and approximately 2 μm in height.

In one embodiment, an image sensor includes a central imaging arrayregion to provide pixelated sensing of an image, in communication with aperipheral region that includes circuitry to provide biasing, readout,analog-to-digital conversion, and signal conditioning to the pixelatedlight sensing region. An optically sensitive material overlies theperipheral region.

In embodiments, the at least one light sensor includes a light-sensingmaterial capable of sensing infrared light.

In embodiments, light impinging on the light-sensing material is to bemodulated.

In embodiments, a portion of light impinging on the light-sensingmaterial is to be generated using a light emitter device having anemission wavelength in the range of about 800 nm to about 1000 nm.

In embodiments, the central imaging array includes at least sixmegapixels.

In embodiments, the central imaging array comprises pixels less thanapproximately 2 μm in width and approximately 2 μm in height.

In embodiments, the optically sensitive material is chosen to include atleast one material from a list, the list including silicon, colloidalquantum dot film, and a semiconducting polymer.

In embodiments, the optically sensitive material is fabricated on afirst substrate, and is subsequently incorporated onto the centralimaging array region.

In one embodiment, a mobile computing device includes a semiconductorsubstrate, an image sensor comprising pixel circuitry formed on thesemiconductor substrate and an image sensing region, a photosensorcomprising read-out circuitry formed on the semiconductor substrate anda light sensitive region, circuitry configured to read an image from theimage sensor, a processor configured to process a signal read from thephotosensor proportional to an optical signal sensed by the photosensor,and control circuitry configured in at least one mode to provide powerto read the photosensor without providing power to read-out the imagesensor such that power consumption is reduced compared to a mode wherethe power is provided to operate the image sensor.

In various example embodiments, the inventive subject matter is an imagesensor and methods of formation of image sensors. In an embodiment, theimage sensor comprises a semiconductor substrate and a plurality ofpixel regions. Each of the pixel regions includes an optically sensitivematerial over the substrate with the optically sensitive materialpositioned to receive light. A pixel circuit for each pixel region isalso included in the sensor. Each pixel circuit comprises a charge storeformed on the semiconductor substrate and a read out circuit. Anon-metallic contact region is between the charge store and theoptically sensitive material of the respective pixel region, the chargestore being in electrical communication with the optically sensitivematerial of the respective pixel region through the non-metallic contactregion.

In various embodiments, an image sensor having at least two pixelelectrodes per color region and at least two modes is disclosed. Theimage sensor comprises a first, unbinned, mode; and a second, binned,mode. In the first, unbinned mode, the at least two pixel electrodes percolor region are to be reset to substantially similar levels. In thesecond, binned mode, a first pixel electrode of the at the least twopixel electrodes is to be reset to a high voltage that results inefficient collection of photocharge, and a second pixel electrode of theat the least two pixel electrodes is to be reset to a low voltage thatresults in less efficient collection of photocharge.

In example embodiments, a continuous optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, a pixellated optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 650 nm with a quantumefficiency exceeding 70% overlies the at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 950 nm with a quantumefficiency exceeding 50% overlies the at least two pixel electrodes.

In various embodiments, an image sensor having m pixel electrodes of afirst class, and n pixel electrodes of a second class, and having atleast two modes, is disclosed. The image sensor comprises a first,unbinned, mode; and a second, binned, mode. In the first, unbinned mode,the m pixel electrodes and the n pixel electrodes of the first andsecond classes are to be reset to substantially similar levels. In thesecond, binned mode, the m pixel electrodes of the first class are to bereset to a high voltage that results in efficient collection ofphotocharge, and the n pixel electrodes of the second class are to bereset to a low voltage that results in less efficient collection ofphotocharge.

In example embodiments, m is equal to 1 per color region, and n is equalto 3 per color region.

In example embodiments, the electrodes are laid out in a 2D hexagonalclose-packed array.

In example embodiments, the electrodes are laid out in a 2D squareclose-packed array.

In example embodiments, m is equal to 1 per color region, and n is equalto 4 per color region.

In example embodiments, m is equal to 1 per color region, and n is equalto 6 per color region.

In example embodiments, a continuous optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, a pixellated optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 650 nm with a quantumefficiency exceeding 70% overlies the at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 950 nm with a quantumefficiency exceeding 50% overlies the at least two pixel electrodes.

In various embodiments, an image sensor having at least two pixelelectrodes per color region, and having at least two modes is disclosed.The image sensor comprises a first, unbinned, mode; and a second,binned, mode. In the second, binned mode, charge collected by a firstpixel electrode is, during a first period, to be switched into a chargestore, and during a second period, to be switched to a low-impedancenode.

In example embodiments, a continuous optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, a pixellated optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 650 nm with a quantumefficiency exceeding 70% overlies the at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 950 nm with a quantumefficiency exceeding 50% overlies the at least two pixel electrodes.

In various embodiments, an image sensor having at least two pixelelectrodes per color region, and having at least two modes is disclosed.The image sensor comprises a first, unbinned, mode; and a second,binned, mode. In the second, binned mode, charge collected by a firstpixel electrode is, in a first submode, is to be switched into a firstcharge store, and, in a second submode, to be switched to a secondcharge store. The first charge store has a capacitance at least twotimes smaller than that of the second charge store.

In example embodiments, a continuous optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, a pixellated optically sensitive layer overliesthe at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 650 nm with a quantumefficiency exceeding 70% overlies the at least two pixel electrodes.

In example embodiments, an optically sensitive layer capable of sensinglight in the range of about 470 nm to about 950 nm with a quantumefficiency exceeding 50% overlies the at least two pixel electrodes.

In various embodiments, an image sensor having at least two colorregions, each color region having at least two modes is disclosed. Theimage sensor comprises a first, unbinned, mode; and a second, binned,mode. In the first, unbinned mode, the at least two pixel electrodes percolor region are to be reset to substantially similar levels. In thesecond, binned mode, the first pixel electrode is to be reset to a highvoltage that results in efficient collection of photocharge, and thesecond pixel electrode is to be reset to a low voltage that results inless efficient collection of photocharge.

In example embodiments, overlying the first color region is an opticallysensitive layer capable of sensing light in a first spectral range witha quantum efficiency exceeding 80%, and further capable of sensing lightin a second spectral range with a quantum efficiency less than 20%; andoverlying the second color region is an optically sensitive layercapable of sensing light in the first spectral range with a quantumefficiency less than 20%, and further capable of sensing light in thesecond spectral range with a quantum efficiency greater than 80%.

In example embodiments, overlying the first color region is an opticallysensitive layer capable of sensing light in a first spectral range witha quantum efficiency exceeding 80%, and further capable of sensing lightin a second spectral range with quantum efficiency less than 20%; andoverlying the second color region is an optically sensitive layercapable of sensing light in the first spectral range with a quantumefficiency less than 20%, and further capable of sensing light in thesecond spectral range with a quantum efficiency greater than 80%.

As a person of ordinary skill in the art will recognize, the variousembodiments described in the specification are provided by means ofexample only so as to describe the disclosed subject matter. Therefore,the examples and embodiments are not to be considered to be limiting.

The present disclosure is therefore not to be limited in terms of theparticular embodiments described in this application, which are intendedas illustrations of various aspects. Many modifications and variationscan be made, as will be apparent to a person of ordinary skill in theart upon reading and understanding the disclosure provided herein.Functionally equivalent methods and devices within the scope of thedisclosure, in addition to those enumerated herein, will be apparent toa person of ordinary skill in the art from the foregoing descriptions.Portions and features of some embodiments may be included in, orsubstituted for, those of others. Many other embodiments will beapparent to those of ordinary skill in the art upon reading andunderstanding the description provided herein. Such modifications andvariations are intended to fall within a scope of the appended claims.The present disclosure is to be limited only by the terms of theappended claims, along with the full scope of equivalents to which suchclaims are entitled. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodiments onlyand is not intended to be limiting.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. The abstractis submitted with the understanding that it will not be used tointerpret or limit the claims. In addition, in the foregoing DetailedDescription, it may be seen that various features may be groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted aslimiting the claims. Thus, the following claims are hereby incorporatedinto the Detailed Description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. An image sensor, comprising: a first pixelelectrode; a second pixel electrode; an optically sensitive layeroverlying the first pixel electrode and the second pixel electrode; andan optical filter continuously overlying the optically sensitive layer,the optical filter to provide substantially the same spectral responsefor light incident on the optically sensitive layer overlying the firstpixel electrode and the second pixel electrode, the image sensor beingconfigured to operate in at least two modes: a first, unbinned, mode;and a second, binned, mode; in the first, unbinned mode, the first pixelelectrode and the second pixel electrode are to be reset tosubstantially similar levels, and in the second, binned mode, the firstpixel electrode is to be reset to a high voltage that results in acollection of photocharge of a first efficiency, and second pixelelectrode is to be reset to a low voltage that results in a collectionof photocharge that is less efficient than the first efficiency.
 2. Theimage sensor of claim 1, wherein the optically sensitive layer thatoverlies the first pixel electrode and the second pixel electrode ispixellated.
 3. The image sensor of claim 1, wherein the opticallysensitive layer is capable of sensing light in the range of about 470 nmto about 650 nm with a quantum efficiency exceeding about 70%.
 4. Theimage sensor of claim 1, wherein the optically sensitive layer iscapable of sensing light in the range of about 470 nm to about 950 nmwith a quantum efficiency exceeding about 50%.
 5. An image sensor,comprising: m pixel electrodes of a first class; n pixel electrodes of asecond class; an optically sensitive layer overlying the m pixelelectrodes and the n pixel electrodes; and an optical filtercontinuously overlying the optically sensitive layer, the optical filterto provide substantially the same spectral response for light incidenton the optically sensitive layer overlying the m pixel electrodes andthe n pixel electrodes, the image sensor being configured to operate inat least two modes: a first, unbinned, mode; and a second, binned, mode;in the first, unbinned mode, the m pixel electrodes and the n pixelelectrodes of the first class and the second class, respectively, are tobe reset to substantially similar levels; and in the second, binnedmode, the m pixel electrodes of the first class are to be reset to ahigh voltage that results in a collection of photocharge of a firstefficiency, and the n pixel electrodes of the second class are to bereset to a low voltage that results in a collection of photocharge thatis less efficient than the first efficiency.
 6. The image sensor ofclaim 5, wherein m is equal to 1 per color region, and n is equal to 3per color region.
 7. The image sensor of claim 5, wherein the electrodesare laid out in a 2D hexagonal close-packed array.
 8. The image sensorof claim 5, wherein the electrodes are laid out in a 2D squareclose-packed array.
 9. The image sensor of claim 5, wherein m is equalto 1 per color region, and n is equal to 4 per color region.
 10. Theimage sensor of claim 5, wherein m is equal to 1 per color region, and nis equal to 6 per color region.
 11. The image sensor of claim 5, whereinthe optically sensitive layer that overlies the m pixel electrodes andthe n pixel electrodes is pixellated.
 12. The image sensor of claim 5,wherein the optically sensitive layer is capable of sensing light in therange of about 470 nm to about 650 nm with a quantum efficiencyexceeding about 70%.
 13. The image sensor of claim 5, wherein theoptically sensitive layer is capable of sensing light in the range ofabout 470 nm to about 950 nm with a quantum efficiency exceeding about50%.
 14. An image sensor, comprising: a first pixel electrode; a secondpixel electrode; an optically sensitive layer overlying the first pixelelectrode and the second pixel electrode; and an optical filtercontinuously overlying the optically sensitive layer, the optical filterto provide substantially the same spectral response for light incidenton the optically sensitive layer overlying the first pixel electrode andthe second pixel electrode, the image sensor being configured to operatein at least two modes: a first, unbinned, mode; and a second, binned,mode; in the second, binned mode, charge collected by the first pixelelectrode is, during a first period, to be switched into a charge store,and during a second period, to be switched to a low-impedance node. 15.The image sensor of claim 14, wherein the optically sensitive layer thatoverlies the first pixel electrode and the second pixel electrode ispixellated.
 16. The image sensor of claim 14, wherein the opticallysensitive layer is capable of sensing light in the range of about 470 nmto about 650 nm with a quantum efficiency exceeding about 70%.
 17. Theimage sensor of claim 14, wherein the optically sensitive layer iscapable of sensing light in the range of about 470 nm to about 950 nmwith a quantum efficiency exceeding about 50%.
 18. An image sensor,comprising: a first pixel electrode; a second pixel electrode; anoptically sensitive layer overlying the first pixel electrode and thesecond pixel electrode; and an optical filter continuously overlying theoptically sensitive layer, the optical filter to provide substantiallythe same spectral response for light incident on the optically sensitivelayer overlying the first pixel electrode and the second pixelelectrode, the image sensor being configured to operate in at least twomodes: a first, unbinned, mode; and a second, binned, mode; in thesecond, binned mode, charge collected by a first pixel electrode, in afirst submode, is to be switched into a first charge store, and, in asecond submode, is to be switched to a second charge store; the firstcharge store having a capacitance at least two times smaller than thatof the second charge store.
 19. The image sensor of claim 18, whereinthe optically sensitive layer that overlies the first pixel electrodeand the second pixel electrode is pixellated.
 20. The image sensor ofclaim 18, wherein the optically sensitive layer is capable of sensinglight in the range of about 470 nm to about 650 nm with a quantumefficiency exceeding about 70%.
 21. The image sensor of claim 18,wherein the optically sensitive layer is capable of sensing light in therange of about 470 nm to about 950 nm with a quantum efficiencyexceeding about 50%.
 22. An image sensor having at least two colorregions, the image sensor comprising: a first pixel electrode; a secondpixel electrode; an optically sensitive layer overlying the first pixelelectrode and the second pixel electrode; and an optical filtercontinuously overlying the optically sensitive layer, the optical filterto provide substantially the same spectral response for light incidenton the optically sensitive layer overlying the first pixel electrode andthe second pixel electrode, the image sensor being configured to operatein the at least two modes: a first, unbinned, mode; and a second,binned, mode; in the first, unbinned mode, the first pixel electrode andthe second pixel electrode per color region are to be reset tosubstantially similar levels; and in the second, binned mode, the firstpixel electrode is to be reset to a high voltage that results in acollection of photocharge of a first efficiency, and the second pixelelectrode is to be reset to a low voltage that results in a collectionof photocharge that is less efficient than the first efficiency.
 23. Theimage sensor of claim 22, further comprising: overlying the first colorregion is an optically sensitive layer capable of sensing light in afirst spectral range with a quantum efficiency exceeding about 80%, andfurther capable of sensing light in a second spectral range with aquantum efficiency less than about 20%; and overlying the second colorregion is an optically sensitive layer capable of sensing light in thefirst spectral range with a quantum efficiency less than about 20%, andfurther capable of sensing light in the second spectral range with aquantum efficiency greater than about 80%.
 24. The image sensor of claim22, further comprising: overlying the first color region is an opticallysensitive layer capable of sensing light in a first spectral range witha quantum efficiency exceeding about 80%, and further capable of sensinglight in a second spectral range with quantum efficiency less than about20%; and overlying the second color region is an optically sensitivelayer capable of sensing light in the first spectral range with aquantum efficiency less than about 20%, and further capable of sensinglight in the second spectral range with a quantum efficiency greaterthan about 80%.